Commas with Nonessential and Parenthetical Elements

In 1967, astrophysicist Jocelyn Bell Burnell detected a series of highly regular radio pulses while analyzing data from a newly constructed telescope. These strange signals, which were initially nicknamed 'Little Green Men' turned out to be the first evidence of rotating neutron stars. Today, these stars, known as pulsars, help astronomers map the structure of our galaxy.

Which of the following options represents the correct punctuation for the underlined portion?

In 1938, a South African museum curator named Marjorie Courtenay-Latimer discovered an unusual blue fish among a local trawler's catch. The specimen, which had lobe-like fins and a three-lobed tail, was later identified as a coelacanth. Scientists were astonished because this lineage of fish was believed to have gone extinct over sixty million years ago.

Which choice correctly punctuates the underlined portion of the passage?

Early mariners relied on the astrolabe, a handheld instrument that calculated latitude by measuring the sun's angle. Navigators who sailed across the Atlantic, which could be unpredictable used the device to chart their courses. By the sixteenth century, this tool had transformed maritime exploration.

Which choice is the correct punctuation for the underlined portion of the passage?

In the fifteenth century, the invention of movable type revolutionized the distribution of knowledge across Europe. Gutenberg’s press, which was developed in Mainz, Germany allowed for the rapid mass production of texts. This dramatic shift in book manufacturing helped lay the groundwork for the Renaissance and the Scientific Revolution.

Which choice best punctuates the underlined portion of the sentence?

Created in the early 1830s, *The Great Wave off Kanagawa* is one of the most recognizable works of Japanese art. The woodblock print, which depicts three boats navigating a towering wave, features the iconic Prussian blue pigment. This masterpiece helped secure Hokusai's legacy as a pioneer in landscape composition.

Which of the following options correctly punctuates the underlined portion of the sentence?

For centuries, the ancient city of Petra remained hidden from the Western world behind a wall of sandstone cliffs. In 1812, Swiss explorer Johann Ludwig Burckhardt, a scholar who was fluent in Arabic finally gained entry to the valley. Disguised as a Bedouin, he successfully bypassed local guards to document the breathtaking ruins.

Which of the following options represents the correct punctuation for the underlined portion of the passage?

The following passage is an excerpt from a science essay.

Tardigrades, microscopic animals famous for their extreme durability, can survive the vacuum of outer space. These organisms, which are also known as water bears enter a state of cryptobiosis when environmental conditions become too harsh. In this dormant state, they can survive without water for decades.

Which choice best punctuates the underlined portion of the sentence?

The Library of Alexandria was renowned for housing the greatest collection of texts in the ancient world. The scroll that detailed the calculations, a rare document, was preserved in the inner sanctuary of the library. Only the chief librarian and senior scholars were permitted to access such invaluable resources.

Which of the following is the best choice for the underlined portion of the sentence?

In 1842, Italian mathematician Luigi Menabrea published a paper on Charles Babbage's Analytical Engine. Ada Lovelace undertook the task of translating this French document into English. The memoir, which she expanded with her own notes, became a landmark in computer science.

Which choice most effectively punctuates the underlined portion of the sentence?

The following passage is an excerpt from an essay about the history of science.

In 1952, British biophysicist Rosalind Franklin produced Photo 51, a high-resolution X-ray diffraction image of DNA. The image that Franklin captured was shown to rival scientists James Watson and Francis Crick without her knowledge or consent. Watson and Crick used this key piece of evidence to determine the double-helix structure of the molecule.

Which of the following punctuation choices for the underlined portion is grammatically correct?

The following passage contains an underlined portion.

During Napoleon’s Egyptian campaign in 1799, French soldiers uncovered a black granodiorite slab that would change history. The Rosetta Stone; which featured a decree written in three different scripts, allowed scholars to compare known Greek text with mysterious hieroglyphs. Consequently, French scholar Jean-François Champollion cracked the code in 1822, opening a window into ancient Egyptian civilization.

Which of the following options is the correct punctuation for the underlined portion in the passage?

Launched by NASA in 1977, the Voyager 1 spacecraft was designed to study the outer solar system. A copper phonograph record, which contains sounds and images selected to portray the diversity of life on Earth, is carried by the probe as it travels into interstellar space. This record is expected to last for billions of years, potentially serving as a message to extraterrestrial civilizations.

Which choice is the correct punctuation for the underlined portion of the passage?

The self-taught paleontologist Mary Anning patrolled the crumbling cliffs of Lyme Regis to search for prehistoric remains. Along the shore, she discovered the first correctly identified ichthyosaur skeleton. This remarkable fossil, which challenged established scientific views about the history of the Earth, paved the way for modern paleontology.

Which choice best punctuates the underlined portion of the sentence?

In 1915, Albert Einstein published his theory of general relativity, which revolutionized modern physics. This groundbreaking work, a mathematical framework that describes gravity as the warping of spacetime, challenged Newton's classical laws. Scientists around the world immediately began testing its predictions.

Which of the following is the best replacement for the underlined portion of the passage?

Based on the passage below, which option represents the most grammatically correct punctuation for the underlined portion?

In 1936, the British mathematician Alan Turing published a landmark paper introducing the concept of a universal machine. This theoretical device, which could perform any computation, laid the foundation for the modern computer. Today, his work is celebrated as the dawn of the information age.

During the 1900 yellow fever epidemic in Havana, Dr. Walter Reed led a U.S. Army commission to identify the transmission method of the deadly disease. Reed's subsequent [1] experiments, which confirmed Carlos Finlay's mosquito hypothesis, saved thousands of lives. This crucial discovery paved the way for the eradication of yellow fever in the region.

Which of the following is the most appropriate punctuation for the underlined portion marked [1]?

The following passage contains an underlined portion.

In 1967, astrophysicist Jocelyn Bell Burnell detected a series of anomalous radio signals while analyzing data from a newly constructed radio telescope. These rapid pulses, which recurred every 1.3 seconds, initially baffled researchers who were searching for cosmic sources. The team jokingly dubbed the mysterious source 'Little Green Men 1' before identifying it as a pulsar, a rapidly spinning neutron star.

Which choice best punctuates the underlined portion of the passage?

In Barcelona, Spain, several architectural masterpieces designed by Antoni Gaudí draw millions of visitors each year. The basilica of La Sagrada Família , which is Gaudí’s most famous work, features towering spires and intricate facades. Construction on this iconic structure began in 1882 and remains unfinished to this day.

Which option represents the most grammatically correct punctuation for the underlined portion of the passage?

In 1897, the Polish-French physicist Marie Curie began investigating uranium rays for her doctoral thesis. The research project, which she conducted in a drafty shed, soon led to the discovery of radioactivity. The materials that she analyzed during these experiments were highly toxic, but her groundbreaking work changed science forever.

Based on the passage, which option represents the most grammatically correct punctuation for the underlined portion?

In the mid-nineteenth century, Ada Lovelace worked closely with Charles Babbage on his plans for the Analytical Engine. Her translation of an article on the machine , which she completed in 1843, contained extensive notes that described the first computer algorithm. Lovelace’s visionary insights earned her a lasting legacy as the world's first computer programmer.

Which option represents the most grammatically correct punctuation for the underlined portion?