Question 92·Medium·Text Structure and Purpose
Researchers investigating ways to reduce the urban heat-island effect have proposed painting rooftops white so that they reflect, rather than absorb, sunlight. Skeptics argue that such large-scale "cool roof" programs would be too costly and deliver only minimal benefits. A recent pilot project in Phoenix, however, recorded average roof-surface temperatures that were 15 degrees Fahrenheit lower after buildings were coated with reflective paint.
Which choice best describes the function of the underlined sentence in the text as a whole?
For “function of a sentence” questions, first read a few lines before and after the sentence to see the flow of ideas. Identify what the author just said (a claim, a problem, an opposing view) and then ask: Is this sentence giving an example, evidence, contrast, explanation, or a new topic? Pay close attention to transition words like “however,” “for example,” or “therefore,” and then eliminate any choices that mention content (like economic impact or new strategies) that the sentence never actually discusses.
Hints
Consider the passage’s structure
Ask yourself: What point is being made right before the bolded sentence, and is the bolded sentence supporting that point, opposing it, or changing the topic?
Focus on the word “however”
Look at how the transition word at the start of the bolded sentence affects its relationship to the skeptics’ argument in the previous sentence.
Think about the type of information given
Is the bolded sentence giving a new problem, a cost prediction, a different strategy, or is it offering data about how well the proposed strategy works?
Eliminate choices that don’t fit the details
Check each answer against the actual content of the bolded sentence: Does that sentence mention economic impact, alternative strategies, or reasons mitigation is needed, or is it doing something else?
Step-by-step Explanation
Identify the main positions in the passage
First, notice the two sides presented:
- Researchers propose painting rooftops white to reduce the urban heat-island effect.
- Skeptics argue that large-scale cool roof programs would be too expensive and offer only minimal benefits. The bolded sentence comes right after the skeptics’ claim, so it likely responds to that claim in some way.
Look closely at the bolded sentence itself
The bolded sentence describes a recent pilot project in Phoenix and gives a specific result: average roof-surface temperatures were 15°F lower after using reflective paint. This is real-world evidence (data) about what actually happened when roofs were painted with reflective paint.
Notice the transition word and its effect
The sentence begins with “however,” which usually signals a contrast or disagreement with what came right before. What came right before? The skeptics’ argument that benefits would be minimal. So the bolded sentence is set up to push back against or modify that skeptical view, not simply add a new point.
Match that role to the best answer choice
The bolded sentence does not introduce a new reason why mitigation is needed (that would focus on why the heat-island effect is a problem), it does not switch to a different strategy than cool roofs, and it says nothing about future economic impact or costs. Instead, it presents evidence (15°F lower temperatures) that challenges the skeptics’ claim that cool roofs have only minimal benefits, thereby softening or qualifying their concerns. Therefore, the correct answer is: It qualifies the skeptics’ concerns by presenting evidence that counters their claims.