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Craft and StructureHardFunction of a sentence

Craft and Structure practice question

Coral reefs cover less than one percent of the ocean floor. Despite this tiny footprint, they shelter roughly a quarter of all marine species. Protecting even a small stretch of reef, then, can safeguard a remarkable share of ocean life.

Which choice best describes the function of the underlined final sentence in the text as a whole?

  1. A. It introduces a counterexample that weakens the earlier claim.
  2. B. It draws a practical conclusion from the contrast presented earlier.Correct
  3. C. It supplies statistics that were missing from the first two sentences.
  4. D. It shifts the discussion to a completely different ecosystem.

Answer: B. It draws a practical conclusion from the contrast presented earlier.

The first two sentences set up a contrast (tiny area, huge biodiversity); the final sentence, signaled by 'then,' draws a practical takeaway about protection from that contrast. It does not weaken the claim (A) or change ecosystems (D), and it adds no new statistics (C).

Why the other answers are wrong

A. It introduces a counterexample that weakens the earlier claim.
The final sentence begins with 'then,' which builds on the earlier facts rather than pushing against them; a counterexample would have to undercut the reef biodiversity claim, and nothing here does.
C. It supplies statistics that were missing from the first two sentences.
The two statistics (less than one percent, roughly a quarter) both appear in the first two sentences — the final sentence adds no numbers at all.
D. It shifts the discussion to a completely different ecosystem.
The sentence stays entirely with reefs and ocean life; no other ecosystem is ever introduced.

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