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Question

Difficulty: MediumSelecting Concluding Sentences and Transitions

[1] In the late 1980s, engineering teams in Japan faced a daunting challenge with the high-speed Shinkansen trains. As the trains exited narrow tunnels at speeds of nearly 200 miles per hour, they compressed the air ahead of them, creating a deafening sound known as a "tunnel boom." This noise not only disturbed nearby residents but also threatened the structural integrity of the tunnels themselves. Eiji Nakatsu, the chief engineer and an avid birdwatcher, realized that the solution might lie in nature.

[2] Nakatsu observed the kingfisher, a bird that dives from the air into water to catch fish with barely a splash. He reasoned that the bird's wedge-shaped beak allowed it to transition smoothly between mediums of different densities. By redesigning the nose of the Shinkansen train to mimic the shape of the kingfisher's beak, the engineers reduced the train's air pressure by 30 percent and noise levels significantly. ________

Which of the following concluding sentences best wraps up the main idea of the passage?

  1. Ultimately, this application of biomimicry not only resolved the acoustic issue but also improved the train’s overall aerodynamic efficiency.Answer
  2. B
    Therefore, engineers began studying other avian species, such as owls and penguins, to see how their feathers might help reduce wind resistance in commercial airplanes.
  3. C
    This design innovation solved the noise problem, it also made the Shinkansen one of the most famous trains in transportation history.
  4. D
    Consequently, the team resolved the acoustic issue, and they will receive an award for their work in 1990.

Answer

Ultimately, this application of biomimicry not only resolved the acoustic issue but also improved the train’s overall aerodynamic efficiency.
The correct answer, which discusses how biomimicry solved the acoustic issue and improved aerodynamic efficiency, is correct because it logically concludes the paragraph by summarizing the resolution of the main challenge (noise and pressure) using the biological concept introduced in the text, all while maintaining grammatical correctness and consistent tense.

Step-by-Step Solution

1
Analyze the passage to identify the central focus and theme.
The passage describes how Japanese engineers solved a specific problem (tunnel boom noise and high air pressure in Shinkansen trains) by mimicking the shape of a kingfisher's beak (biomimicry).
Understanding the core topic prevents choosing options that drift into unrelated concepts.
2
Evaluate the grammar and structure of each option.
Identify that the option containing a comma splice is grammatically incorrect, and the option with the future tense shift is inconsistent with the historical context of the passage.
ACT English questions require sentences to be both rhetorically effective and grammatically correct.
3
Determine which grammatically correct option best summarizes the passage without introducing new details.
The option highlighting that the biomimicry design resolved the acoustic issue and improved aerodynamic efficiency correctly summarizes the train's design changes without introducing external details about other vehicles or animals.
An effective conclusion must wrap up the main ideas of the passage rather than introduce new research directions.

Key Concept

Selecting Concluding Sentences
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Topics

Selecting Concluding Sentences and Transitions

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