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Question

Difficulty: Very hardSupporting Claims with Evidence and Details

Passage

[1] In the mid-twentieth century, geologist Marie Tharp painstakingly plotted sonar soundings to draft the first comprehensive maps of the ocean floor. [2] Although her male colleagues initially dismissed her findings as "girl talk," Tharp's meticulous charts revealed a massive, continuous rift valley splitting the Mid-Atlantic Ridge. [3] This distinct geological feature provided the crucial physical mechanism needed to support the continental drift theory. [4] To solidify this revolutionary claim, researchers needed to present clear, observable proof of volcanic activity and seafloor spreading occurring along this underwater rift.

Question

The writer wants to add a sentence at the end of the passage (following Sentence 4) to support the claim that volcanic activity and seafloor spreading were actively occurring along the Mid-Atlantic Ridge's rift valley. Which of the following sentences would best provide the most specific and concrete visual evidence to support this claim?

  1. A
    By deploying deep-sea cameras, hydrothermal vents spewing mineral-rich water were photographed by the research team along the valley floor.
  2. Submersible cameras captured images of towering hydrothermal vents billowing dark, mineral-rich plumes and fresh basalt pillows glass-like from rapid cooling.Answer
  3. C
    Expeditions collected various geological samples and data points from several locations along the Mid-Atlantic Ridge to analyze the seafloor's crustal age.
  4. D
    Scientists documented active geological processes; which showed that tectonic plates were moving apart at a rate of several centimeters per year.

Answer

The option describing submersible cameras capturing images of towering hydrothermal vents and glass-like basalt pillows.
The option describing submersible cameras capturing images of towering hydrothermal vents billowing dark, mineral-rich plumes and fresh basalt pillows is correct because it is grammatically sound and directly fulfills the prompt's request for specific, concrete visual evidence of volcanic activity and seafloor spreading. The visual descriptors (towering, billowing, glass-like) provide the most detailed proof compared to general assertions.

Step-by-Step Solution

1
Identify the prompt's main rhetorical and content constraints.
The target sentence must support the claim that volcanic activity and seafloor spreading were actively occurring, and it must do so using the most specific, concrete visual details.
This establishes the criteria for evaluating the choices and eliminates options that do not focus on specific visual details or active processes.
2
Examine the grammatical correctness of each option to eliminate structural errors.
The option beginning with 'By deploying...' is eliminated due to a dangling modifier, and the option containing a semicolon before 'which showed...' is eliminated due to a semicolon fragment error.
ACT English questions require the correct option to be free of all grammatical and punctuation errors.
3
Compare the remaining grammatically correct options for visual specificity.
The option describing towering hydrothermal vents billowing dark plumes and glass-like basalt pillows is chosen over the option describing generalized expeditions collecting samples and data.
The descriptive details in the correct option provide concrete visual evidence of active volcanic activity, satisfying the prompt's request for high specificity over generalization.

Key Concept

Supporting claims with specific, concrete visual evidence and details, while maintaining strict grammatical accuracy.
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Topics

Supporting Claims with Evidence and Details

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