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Difficulty: MediumParagraph-Level Transitions

The following paragraphs are from an essay about deep-sea hydrothermal vents.

Paragraph 1
In 1977, oceanographers exploring the Galapagos Rift made a discovery that fundamentally altered our understanding of biology. Using the research submersible *Alvin*, they descended more than 8,000 feet below the ocean surface, where water temperatures are near freezing and sunlight never penetrates. There, they found hydrothermal vents spewing mineral-rich, superheated water. Surprisingly, these vents were surrounded by thriving ecosystems of giant tube worms, clams, and crabs.

Paragraph 2
Prior to this expedition, it was widely accepted that all food webs relied on solar energy. [1] Near the vents, however, specialized bacteria generate energy by oxidizing toxic hydrogen sulfide, a process called chemosynthesis. These microbes form the base of a unique food chain, demonstrating that complex life can flourish without any sunlight at all.

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

  1. NO CHANGEAnswer
  2. B
    During the expedition, oceanographers find that the water near the vents was incredibly hot.
  3. C
    Prior to this expedition, scientists believed life required sunlight, they had no idea chemosynthesis existed.
  4. D
    Deep-sea creatures must adapt to extreme conditions, such as high pressure and complete darkness.

Answer

NO CHANGE
The correct option is correct because it successfully connects the ecosystems discovered on the expedition (mentioned in the preceding paragraph) to the chemical process that sustains them (introduced in the following paragraph) by contrasting it with the traditional solar-based model.

Step-by-Step Solution

1
Identify the relationship between the two paragraphs.
Paragraph 1 describes the discovery of thriving deep-sea ecosystems. Paragraph 2 explains the biological process of chemosynthesis that sustains them. A successful transition must bridge these two points.
This establishes the rhetorical purpose of the transition.
2
Evaluate the choices for grammatical correctness.
The option containing a comma splice is grammatically incorrect. The option with a tense shift ('find' instead of 'found') is also grammatically incorrect.
This allows for the elimination of grammatically flawed options.
3
Determine which grammatically correct choice provides the best transition.
The choice stating that food webs were previously believed to rely on solar energy sets up the explanation of chemosynthesis, whereas the option focusing on adaptations does not.
This selects the option that best fulfills the rhetorical goal.

Key Concept

Selecting transitional sentences that logically bridge paragraphs while maintaining grammatical correctness.
Estimated Time:1m 0s
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Topics

Paragraph-Level Transitions

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