Question 50·Medium·Rhetorical Synthesis
While researching a topic, a student has taken the following notes:
- Coral reefs are underwater structures built by tiny animals called coral polyps.
- Coral polyps secrete calcium carbonate skeletons that accumulate to form reefs.
- Roughly 25% of all marine species depend on coral reefs for food or shelter.
- Coral reefs are sometimes called the "rainforests of the sea."
The student wants to write a sentence that both defines coral reefs and highlights their ecological importance. Which choice most effectively uses relevant information from the notes to accomplish this goal?
For questions that give you research notes and ask for a sentence, first underline the exact task (for example, “define X and explain its importance”). Next, label each note as definition, process, example, or significance. Then scan the answer choices and eliminate any that (1) include information not supported by the notes, (2) satisfy only part of the task (for instance, define but don’t show importance), or (3) ignore the strongest, most specific details (like key numbers or vivid phrases). Choose the option that is accurate, concise, and uses the most relevant, specific notes to meet every part of the goal.
Hints
Clarify the writing goal
Underline the two things the sentence must do: (1) define coral reefs and (2) highlight their ecological importance. Any answer that doesn’t clearly do both should be eliminated.
Match notes to each part of the goal
Look back at the bullet points: which ones tell you what coral reefs are and how they form, and which ones tell you why they matter so much to marine life?
Look for the most specific, powerful information
Among the notes, which details most strongly show how important coral reefs are (think about numbers or vivid comparisons), and which choices actually include those details?
Eliminate partial matches
If a choice only focuses on how reefs form or only focuses on their importance, or leaves out the most specific information from the notes, cross it out.
Step-by-step Explanation
Identify the task in the question
The question says the student wants one sentence that both:
- Defines coral reefs (what they are / what they are made of / who builds them), and
- Highlights their ecological importance (why they matter for marine life).
Any correct answer must clearly do both of these things using information from the notes.
Sort the notes into “definition” and “importance”
Look at what each note tells you:
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Definition / structure notes:
- "Coral reefs are underwater structures built by tiny animals called coral polyps."
- "Coral polyps secrete calcium carbonate skeletons that accumulate to form reefs."
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Ecological importance notes:
- "Roughly 25% of all marine species depend on coral reefs for food or shelter."
- "Coral reefs are sometimes called the 'rainforests of the sea.'" (This nickname suggests high biodiversity and importance.)
The best sentence should combine at least one idea from the definition group and at least one idea from the importance group, without adding wrong or extra information.
Check each choice against the goal and the notes
Now see what each option actually does:
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Choice A: Explains the secretion of calcium carbonate and says many animals rely on reefs, but it never directly defines coral reefs as structures or mention how many species depend on them. It partly meets both goals but is vague on importance and missing the clear structural definition.
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Choice B: Says coral reefs are underwater and built by coral polyps (good for definition) and that they form structures "vital to marine life" (importance), but it does not use the strong quantitative detail (about 25%) or the vivid nickname from the notes. It uses less of the most specific, powerful information.
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Choice C: Mentions that 25% of marine species live in coral reefs and that reefs are made of calcium carbonate skeletons, but it never says that tiny animals called coral polyps build them or that reefs are underwater structures. The definition is incomplete.
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Choice D: Combines what reefs are made of and who builds them with how ecologically important they are, and also includes the descriptive nickname from the notes. It uses multiple key ideas from both the definition and importance groups in a single, clear sentence.
Select the sentence that best fulfills both purposes
The only option that fully defines coral reefs (built from calcium carbonate skeletons secreted by coral polyps) and strongly highlights their ecological importance (they sustain about a quarter of all marine species, reinforced by the phrase "rainforests of the sea") is choice D:
"Coral reefs, sometimes called the 'rainforests of the sea,' are built from calcium carbonate skeletons secreted by coral polyps and sustain about a quarter of all marine species."