Question 20·Medium·Central Ideas and Details
Urban ecologist Maria Ortiz argues that the current enthusiasm for green roofs—buildings topped with soil and vegetation—rests on an incomplete understanding of their benefits. She notes that early studies highlighted green roofs’ ability to lower building energy use, but more recent measurements show that this effect is significant only in temperate climates. In arid cities, the water required to sustain rooftop plants can exceed the energy savings the plants provide. Ortiz therefore calls for local cost-benefit analyses before cities subsidize green-roof installations.
Based on the text, which statement best summarizes Ortiz’s central claim?
For central-claim questions, first quickly summarize the passage in your own words, then pay special attention to the first and last sentences, and any signal words like "therefore," "thus," or "so," which often introduce the main conclusion. Ask yourself: "Given all this evidence, what overall point is the author trying to make or what recommendation are they giving?" Next, eliminate answer choices that add new ideas not in the passage (like motives, aesthetics, or specific solutions) or that zoom in on a single example instead of the overall argument. Choose the option that best captures the author’s broad conclusion or recommendation, even if it uses slightly different wording.
Hints
Find the conclusion signal word
Look for words like "therefore" or "so" that show the author is drawing a conclusion. Which sentence contains that signal?
Differentiate evidence from main point
Ortiz talks about early studies, temperate climates, and arid cities. Ask yourself: are these her main point, or are they supporting reasons that lead to a broader recommendation?
Check for ideas that are not in the passage
Scan the answer choices and see whether any mention topics the passage never discusses, such as motivations of researchers, beauty of roofs, or specific plant types. Those are red flags.
Focus on what she wants cities to do
In the final sentence, Ortiz says what she thinks cities should do regarding subsidies for green roofs. Which answer choice describes that overall recommendation?
Step-by-step Explanation
Identify what the question is asking
The question asks for Ortiz’s central claim. That means you’re looking for the main point or overall argument of the entire passage, not a small detail or an example.
Summarize the passage in your own words
Briefly restate each part:
- Ortiz says enthusiasm for green roofs is based on an incomplete understanding of their benefits.
- Early studies emphasized energy savings from green roofs.
- Newer data show those savings are large only in temperate climates.
- In arid cities, the water needed for rooftop plants can be more costly than the energy they save.
- Because of this, she gives a recommendation in the last sentence about what cities should do before subsidizing green roofs.
Locate the author’s conclusion
Look closely at the final sentence: it begins with "Ortiz therefore...". Words like "therefore" signal a conclusion drawn from the previous evidence. Her conclusion is a recommendation about what cities should do before they subsidize green roofs, based on local costs and benefits.
Match that conclusion to the best answer choice
Now compare each answer choice to that conclusion:
- Eliminate choices that claim intentional deception, mention aesthetics, or suggest specific planting strategies—none of that is in the passage.
- The only option that reflects her recommendation that cities make decisions based on local cost-benefit analysis before adopting or subsidizing green roofs is: “Green roofs should not be adopted until city-specific analyses confirm that their benefits outweigh their costs.”