Selecting Concluding Sentences and Transitions

Modern concrete relies on Portland cement, a binding agent that degrades over decades, especially in marine environments. In contrast, ancient Roman harbor structures built with a mixture of volcanic ash, lime, and seawater have survived for over two millennia. Geologists studying these ancient piers have discovered that seawater actually strengthens the concrete over time. The key lies in a rare mineral called aluminous tobermorite, which crystallizes within the concrete as seawater percolates through the porous structures.

This crystallization process occurs when the alkali-rich seawater reacts with the volcanic ash components. Instead of causing cracks as it would in modern steel-reinforced concrete, the growth of these mineral crystals reinforces the structural matrix. This self-healing mechanism represents a paradigm shift in materials science, prompting researchers to develop modern analogues that mimic this ancient durability. [4]

Which choice provides the most effective conclusion to the paragraph and passage by summarizing the main finding about Roman concrete and emphasizing its implications for the future of engineering?

In the early nineteenth century, Sophie Blanchard became one of France’s most celebrated aeronauts. While her late husband, Jean-Pierre Blanchard, had pioneered ballooning, Sophie carved out her own legacy by performing daring solo flights before massive crowds. She specialized in night ascents, often launching fireworks from her hydrogen balloon, which dazzled spectators across Europe. Emperor Napoleon Bonaparte was so impressed by her skills that he appointed her the Official Aeronaut of the Empire.

The writer wants to conclude the paragraph with a sentence that emphasizes Sophie Blanchard's status as a pioneering and successful solo aeronaut, while tying back to the paragraph's focus on her achievements. Which choice best accomplishes this goal?

In 1943, marine engineer Richard James was working in a Philadelphia shipyard, trying to develop a spring that could stabilize sensitive naval instruments during storms. While working, he accidentally knocked one of his experimental steel springs off a shelf. To his amazement, the spring did not merely fall; it gracefully stepped down a stack of books, onto a tabletop, and then coiled itself upright on the floor. James immediately realized that this walking spring could make a wonderful toy. He and his wife, Betty, spent the next two years developing the product, eventually naming it the 'Slinky.' In 1945, they demonstrated the toy at a local department store, and all 400 units sold out within ninety minutes.

The writer wants to add a concluding sentence that emphasizes the toy's widespread and lasting popularity. Which choice best accomplishes this goal?

For decades, musicologists and collectors have debated the authenticity of several highly prized violins attributed to Antonio Stradivari. Traditional authentication relies heavily on stylistic analysis—examining the varnish, the carving of the scroll, and the geometry of the sound holes. However, these subjective methods can be imprecise and easily deceived by expert counterfeiters. To address this, researchers turned to dendrochronology, the science of analyzing tree-ring growth patterns. By comparing the wood's growth rings to historical climate records, scientists can establish the exact calendar years during which the spruce and maple trees used to construct the instruments grew.

This technique has proved invaluable for verifying the age of historic instruments. For instance, when researchers examined the famous "Messiah" Stradivarius, they analyzed the tree rings on its spruce top. The growth patterns matched tree-ring databases from the Alpine regions, confirming that the wood was harvested in the early eighteenth century, aligning perfectly with Stradivari's lifetime.

Which of the following choices best concludes the passage by reinforcing the idea that dendrochronology provides a reliable, scientific method of authentication?

In 1995, conservationists reintroduced gray wolves to Yellowstone National Park, hoping to restore balance to an ecosystem that had suffered in their seventy-year absence. Without an apex predator, elk populations had swelled, leading to severe overgrazing of willow and aspen trees along riverbanks. The return of the wolves quickly corrected this imbalance; as they hunted the elk, the herbivores were forced to move more frequently and avoid open valleys. Consequently, the streamside vegetation regenerated, stabilizing the soil and providing habitats for songbirds, beavers, and fish. ______

Which choice most effectively concludes the paragraph by emphasizing the widespread and interconnected ecological impact of the wolves' reintroduction?

Art conservators restoring Renaissance frescoes have historically relied on chemical solvents and physical scraping, both of which risk stripping away delicate pigments. Recently, however, laser ablation has emerged as a revolutionary tool in art conservation. By emitting brief pulses of light at precise wavelengths, lasers can vaporize layers of soot and dirt without heating the underlying paint. Because different materials absorb light at distinct rates, the laser can be calibrated to target only the dark grime while reflecting harmlessly off the lighter mineral pigments of the fresco.

Therefore, this absorption process is self-limiting, it prevents accidental over-cleaning. Once the dark soot is removed, the laser no longer has any effect on the surface. Ultimately, this synthesis of physics and art history ensures that these fragile masterpieces are preserved with unprecedented accuracy, allowing them to endure for future generations.

Which choice provides the most logical and effective transition from the preceding paragraph?

The following passage is an excerpt from an essay about deep-sea exploration.

In 1977, oceanographers aboard the research vessel *Alvin* descended into the Pacific Ocean near the Galápagos Islands, expecting to find nothing more than a barren, frozen seafloor. To their astonishment, they discovered hydrothermal vents—fissures in the Earth's crust spewing superheated, mineral-rich water. Surrounding these vents were thriving ecosystems teeming with giant tube worms, blind crabs, and ghost-white fish. This discovery revolutionized biology, showing that life could flourish in the complete absence of sunlight by relying on chemosynthesis, a process in which microbes convert toxic chemicals into energy. [1]

The writer wants to add a concluding sentence at point [1] that summarizes the main idea of the paragraph and reinforces the revolutionary impact of the discovery on scientific understanding. Which choice best accomplishes this goal?

In 1857, French inventor Édouard-Léon Scott de Martinville patented the phonautograph, the earliest known device for recording sound. Unlike Thomas Edison's phonograph, which could both record and play back audio, Scott's invention was designed only to write sound waves onto soot-coated paper. Scott believed that these visual transcriptions, which he called "phonautograms," could eventually be read by eye. Consequently, because he never intended for his recordings to be heard, they remained silent, unplayed artifacts for over a century.

In 2008, scientists at the Lawrence Berkeley National Laboratory utilized digital scanning technology to examine Scott's surviving papers. By mapping the soot patterns and translating them into digital audio files, they successfully recovered the voice of a woman singing the French folk song "Au Clair de la Lune." [1]

The writer wants to add a sentence at [1] to conclude the passage by emphasizing the historic significance of Scott's invention. Which choice most effectively accomplishes this goal?

Termites are master builders, constructing towering mounds that can reach up to thirty feet in height on the African savanna. Despite the scorching daytime heat, the temperature inside these mounds remains remarkably stable. This thermal regulation is achieved through a complex network of vents and tunnels that facilitate passive ventilation. Warm air rises and escapes through a central chimney, while cooler air is drawn in at the base.

Which of the following sentences, if added at the end of the paragraph, would provide the most effective conclusion to the paragraph?

During the nineteenth century, the printing industry underwent rapid technological growth, demanding faster methods for producing newspapers and books. To speed up the typesetting process, workers cast commonly used phrases or words into single metal plates rather than composing them letter by letter. These cast plates were named after the clicking sound made during their creation: clichés. The term eventually transitioned from a technical printing word to a metaphor for overused expressions.

Which choice most effectively concludes the paragraph by reinforcing the relationship between the origin of the term 'cliché' and its current definition?

The following passage is an excerpt from an essay about ancient manuscripts.

In 1906, Danish philologist Johan Ludvig Heiberg examined a medieval prayer book in Istanbul and made a startling discovery: underneath the thirteenth-century religious texts lay much older, partially erased mathematical treatises by the ancient Greek mathematician Archimedes. This unique manuscript, known as the Archimedes Palimpsest, contained the only surviving copy of *The Method of Mechanical Theorems*, in which Archimedes anticipated modern calculus by using infinitesimals to calculate areas and volumes.

To read the faint, overwritten script, modern conservators utilized multispectral imaging, a technology that captures images under various wavelengths of light to expose the chemical differences between the two layers of ink. This non-invasive method successfully revealed lost pages of Archimedes's works alongside commentaries on Aristotle. [Underlined: Fortunately, the book was preserved through the centuries despite its poor condition.]

The writer wants to conclude the passage with a sentence that emphasizes the significance of the recovery of the Archimedes Palimpsest and summarizes the main themes of the passage. Which choice best accomplishes this goal?

The following passage is an excerpt from an essay about digital audio preservation.

In the late 1990s, physicist Carl Haber attended a lecture detailing the inevitable decay of historical audio media. Intrigued by the challenge of preserving fragile wax cylinders and shellac discs, Haber realized that the same optical scanning techniques used in subatomic particle physics could be applied to sound. This insight led to the development of IRENE, a non-contact system that uses high-resolution cameras to capture 3D digital images of a record's physical grooves. Specialized software then translates these visual maps back into audio files, completely bypassing the need for a physical needle. By avoiding physical contact with the fragile media, researchers have successfully reconstructed audio from severely damaged cylinders that were once considered unplayable.

The writer wants to conclude the paragraph with a sentence that emphasizes how IRENE's optical technology has rescued historical recordings that were previously thought to be permanently lost. Which choice best accomplishes this goal?

In 1938, Ruth Wakefield, co-owner of the Toll House Inn in Massachusetts, made a culinary discovery that would change American dessert history. While preparing a batch of chocolate desserts, she chopped up a bar of semi-sweet chocolate and added the pieces to her cookie dough, expecting them to melt and create chocolate cookies. Instead, the chocolate bits retained their shape, resulting in the very first chocolate chip cookies.

The writer wants to add a concluding sentence to the paragraph that wraps up the main point of the passage and emphasizes the lasting impact of Wakefield's accidental invention. Which of the following sentences best accomplishes this goal?

In 1968, Dr. Spencer Silver, a chemist at 3M, developed a "low-tack" adhesive that stuck lightly to surfaces and could be easily removed without leaving residue. For years, Silver promoted his invention within the company, but no one could find a practical use for it. The breakthrough came in 1974 when colleague Art Fry used the adhesive to keep bookmarks from falling out of his hymnal during choir practice. Fry realized that the sticky paper was perfect for leaving temporary notes on documents. [1]

The writer wants to conclude the paragraph at point [1] with a sentence that highlights the subsequent commercial success and global popularity of the invention. Which option best achieves this goal?

Honeybees have developed a sophisticated method of communication known as the waggle dance. When a scout bee finds a rich source of nectar, she returns to the hive and performs a series of figure-eight movements. By angling her body relative to the sun and varying the duration of the central 'waggle' run, she tells her hive mates both the direction and the distance to the flower patch.

The writer wants to add a concluding sentence to the paragraph that summarizes the paragraph's main focus on the honeybees' communication method. Which of the following sentences best achieves this goal?

Passage:

For centuries, the periodic emergences of Magicicada species—commonly known as periodical cicadas—have fascinated and bewildered biologists. Emerging from their subterranean habitats in massive swarms only once every 13 or 17 years, these insects overwhelm predators through sheer volume. In mathematical biology, researchers have long hypothesized that the prime-numbered lengths of these cycles prevent synchronization with the shorter, cyclical life stages of avian predators. By emerging at prime intervals, the cicadas minimize the frequency of overlapping years with predators whose populations fluctuate on 2-, 3-, or 4-year cycles.

To test this evolutionary hypothesis, computer models have simulated interactions between cicadas and hypothetical predators over tens of thousands of evolutionary generations. The simulations consistently demonstrate that cicada populations with non-prime cycles are rapidly driven to extinction by predators that adapt to their predictable cycles, whereas those with prime cycles survive. This computational evidence supports the theory that numerical primes act as an evolutionary shield, ensuring the cicadas' long-term survival.

Given that all the choices are true, which choice provides the most effective concluding sentence for the paragraph and the passage?

During a freezing winter trip to New York City in 1903, Alabama native Mary Anderson noticed that streetcar drivers had to open their front windows or step outside to clear ice and sleet from their windshields, endangering themselves and their passengers. This hazardous situation inspired her to design a rubber squeegee blade operated by a hand lever inside the vehicle. Anderson was granted a patent for her window-cleaning device in 1903, yet manufacturing firms rejected her invention, believing it would distract drivers. Consequently, she never profited from her creation, and the patent eventually expired. [1]

The writer wants to add a sentence at the end of the passage (at point [1]) to conclude the discussion of Mary Anderson's invention. Which choice best accomplishes this goal by summarizing the main significance of her design while remaining consistent with the passage's tone and details?

In the mid-twentieth century, scholars of Maya hieroglyphic writing widely believed that the inscriptions on stone monuments, or stelae, were purely astronomical calendars and mystical calculations. The prevailing view, championed by leading Mayanist J. Eric S. Thompson, held that the Maya were a peaceful, time-obsessed people whose writing did not record historical events or individuals. However, Tatiana Proskouriakoff, an architect and archaeologist, challenged this consensus through meticulous spatial and temporal analysis of the stelae at Piedras Negras. By plotting the dates inscribed on consecutive monuments, she discovered that the timespans between key dates corresponded perfectly to the natural length of a human life. Proskouriakoff proposed that these monuments actually commemorated the lifespans, accessions, and military victories of historical rulers.

The writer wants to conclude the passage with a sentence that reinforces the significance of Proskouriakoff's discovery and ties back to the paragraph's discussion of Maya writing. Which of the following sentences best accomplishes this goal?

A researcher is writing a short article about the history of medicine:

When Alexander Fleming returned to his laboratory after a vacation in 1928, he noticed something unusual in one of his petri dishes. A patch of mold had grown, and the bacteria immediately surrounding it had been destroyed. This accidental observation led to the discovery of penicillin, the world's first antibiotic.

Which choice best concludes the paragraph by emphasizing the historical significance of Fleming's discovery?

In 1977, oceanographers exploring the Galapagos Rift made a startling discovery. Deep on the ocean floor, where no sunlight could penetrate, they found hydrothermal vents spewing superheated, mineral-rich water. Instead of finding a barren wasteland, they observed thriving ecosystems teeming with giant tube worms, blind crabs, and vast colonies of bacteria. These organisms did not rely on photosynthesis; instead, they survived on chemical energy through a process called chemosynthesis.

The writer wants to add a concluding sentence to the paragraph that wraps up the discussion of chemosynthesis and reinforces the main idea of the passage (that this discovery revealed a new way life can thrive without sunlight). Which of the following sentences best accomplishes this goal?