Question 14·Medium·Text Structure and Purpose
Coral bleaching—the loss of symbiotic algae that corals rely on for nourishment—has become more frequent as ocean temperatures rise. Scientists suspect that stressors other than heat may intensify bleaching events. To determine whether local nutrient pollution exacerbates bleaching, the researchers compared two nearby reefs—one exposed to agricultural runoff and one isolated from human activity. After several months of monitoring, they found that coral colonies at the nutrient-rich site bleached sooner and recovered more slowly than colonies at the pristine site.
Which choice best describes the function of the underlined sentence?
For SAT "function of a sentence" questions, first isolate the sentence and decide what type of role it plays: definition/background, description of a method or setup, presentation of evidence or results, explanation/interpretation, or contrast/counterpoint. Then look at its position in the paragraph and how it connects to the sentences before and after. Finally, eliminate choices that describe a type of information (like history, results, or an argument) that is clearly not present in the sentence, and select the option whose description matches what the sentence is actually doing.
Hints
Focus on the underlined sentence alone
Ignore the answer choices at first and reread just the underlined sentence. Ask yourself: what information is this sentence giving—background, what the scientists did, what they found, or how they feel?
Check its position in the paragraph
Notice that one sentence comes before and one comes after the underlined sentence. What does the first sentence do? What does the last sentence do? How does the underlined sentence connect them?
Look for clue phrases
Pay close attention to phrases like "To determine whether" and "the researchers compared." What do these phrases usually signal in a scientific description—past history, study setup, results, or opinions?
Eliminate answers that don’t match the content
Ask of each option: Does the underlined sentence actually give that kind of information (history, results, argument), or is it doing something else? Cross off any choice that mentions a type of information the sentence does not contain.
Step-by-step Explanation
Restate what the underlined sentence says
Focus only on the underlined sentence:
"To determine whether local nutrient pollution exacerbates bleaching, the researchers compared two nearby reefs—one exposed to agricultural runoff and one isolated from human activity."
This sentence tells us why the researchers did something ("To determine whether...") and what they did ("compared two nearby reefs" with different conditions).
Decide what kind of information it gives
Ask: Is this sentence giving background history, describing what researchers did, giving results, or making an argument?
Here, it:
- States a goal: "To determine whether..."
- Describes an action: comparing two types of reefs.
That means it is mainly explaining the setup of the study and how they are investigating a specific question.
Connect it to the rest of the paragraph
Look at the sentences around it:
- The first sentence explains what coral bleaching is and that it has become more frequent.
- The second (underlined) sentence describes how researchers set up a comparison between two reefs.
- The third sentence gives what they found: which corals bleached sooner and recovered more slowly.
So the underlined sentence bridges from the general problem (bleaching and possible stressors) to how they tested one possible cause (nutrient pollution). It is not reporting the outcome; that comes afterward.
Match this role to the correct answer choice
Now match that function to the answer choices:
- It is not about past "history" of research (eliminates A).
- It is not presenting an "unexpected outcome" (the findings come later, eliminates B).
- It does not challenge an assumption; instead it sets up a test of a suspicion (eliminates C).
The only choice that fits is D: It outlines a method the researchers used to examine a possible cause of coral bleaching.