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Question

Difficulty: HardSelecting Concluding Sentences and Transitions

Marie Tharp's career in cartography began at a time when women were barred from conducting research aboard vessels. Staying behind at Columbia University, Tharp transformed raw sonar data collected by her colleague Bruce Heezen into detailed three-dimensional drawings of the ocean floor. By meticulously plotting these depth measurements, she discovered a massive V-shaped rift valley running down the center of the Mid-Atlantic Ridge. While Heezen initially dismissed her findings as "girl talk" that supported the then-controversial theory of continental drift, Tharp persisted, eventually convincing him that the valley was real.

The writer wants to add a sentence at the end of the passage to conclude the paragraph by summarizing the significance of Tharp's discovery. Which choice best accomplishes this goal?

  1. A
    In spite of this, her draft of the Atlantic ridge is widely celebrated today, and future scientists will continue to study her cartographic methods.
  2. B
    Consequently, Tharp's work proved that the continental plates were moving, she was later awarded the Hubbard Medal by the National Geographic Society.
  3. This detailed map provided the visual evidence needed to validate seafloor spreading, which ultimately established the foundation for the modern theory of plate tectonics.Answer
  4. D
    Furthermore, her persistence ensures that geologic research departments opened their doors to female scientists, who would publish groundbreaking papers in the decades that followed.

Answer

The choice that explains how Tharp's map provided the visual evidence needed to validate seafloor spreading and establish the foundation for plate tectonics.
The correct option successfully summarizes the significance of Tharp's work (the map) by connecting her discovery of the rift valley directly to the validation of seafloor spreading and plate tectonics, which were the central subjects of the passage. It remains grammatically correct and flows logically from the preceding sentence.

Step-by-Step Solution

1
Identify the primary topic and thesis of the paragraph.
The paragraph focuses on Marie Tharp's mapping work, specifically her discovery of the Mid-Atlantic Ridge's rift valley, and how it supported the controversial theory of continental drift.
An effective concluding sentence must tie directly back to the main thesis of the passage without introducing unsupported or peripheral details.
2
Evaluate the transitions and logical flow of the options.
The option starting with 'In spite of this' incorrectly uses a contrasting transition immediately after Tharp succeeds in convincing her colleague. The option starting with 'Consequently' uses a cause-and-effect transition but leads into an unrelated clause about awards. The option starting with 'This detailed map' logically continues the narrative flow by explaining the impact of the map.
Concluding sentences must transition logically from the preceding sentence.
3
Check the remaining options for grammatical errors and thematic relevance.
The option starting with 'Consequently' is a comma splice, joining two independent clauses with only a comma. The option starting with 'Furthermore' contains an inconsistent present-tense shift ('ensures') and shifts the paragraph's focus to general academic sexism. The option starting with 'This detailed map' is grammatically correct and directly summarizes the scientific significance of her work.
The correct choice must be grammatically correct and keep the focus on the main topic.

Key Concept

Selecting Concluding Sentences
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Topics

Selecting Concluding Sentences and Transitions

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