Question 2·Medium·Central Ideas and Details
Urban planners have long suggested that tree canopy coverage improves city dwellers’ well-being, but the strength of this link has remained uncertain. Psychologist Lila Nguyen analyzed health records and satellite imagery from 200 neighborhoods in three major cities. After controlling for income, age distribution, and access to healthcare, she found that neighborhoods with higher percentages of mature tree canopy had significantly lower rates of reported anxiety disorders. Nguyen concluded that increasing urban tree coverage could be an effective public-health strategy.
Which choice best states the main idea of the text?
For SAT Reading main idea questions, first read the entire passage carefully, then pause and summarize it in one simple sentence in your own words (who did what, and what did they conclude). Next, scan each answer choice and immediately cross out any that (1) contradict clear facts from the passage, (2) reverse relationships (like switching cause and effect or saying the opposite group is important), or (3) introduce new details or technical claims that the passage never mentions. Among the remaining choices, pick the one that best matches both the key result and the author’s or researcher’s conclusion; avoid answers that focus on a minor detail instead of the overall point.
Hints
Focus on the overall message
Reread the first and last sentences of the passage. How does the study’s result relate to the idea that trees might improve well-being?
Identify Nguyen’s main finding
Ask yourself: after controlling for income, age, and healthcare access, what relationship did Nguyen actually observe between tree canopy and anxiety disorders?
Watch out for reversals and new information
Check each answer for claims that reverse the relationships (for example, saying something else is more important than tree coverage) or introduce new ideas that the passage never mentions (like detailed comparisons that don’t appear in the text).
Match the answer to both the result and the conclusion
Make sure the choice you pick reflects both Nguyen’s research finding and the conclusion she draws about public health, not just one or the other.
Step-by-step Explanation
Clarify what the question is asking
The question asks: “Which choice best states the main idea of the text?”
For main idea questions, you should focus on the overall point of the entire passage, not a small detail. Ask yourself: If I had to summarize this paragraph in one sentence, what would it be?
Summarize the passage in your own words
Briefly restate the key information:
- Urban planners have long suggested that tree canopy helps city well-being, but the strength of this link was uncertain.
- Nguyen conducted a study using health records and satellite images from 200 neighborhoods in three cities.
- She controlled for (held constant) income, age distribution, and access to healthcare.
- She found that neighborhoods with more mature tree canopy had significantly lower anxiety disorder rates.
- She concluded that increasing urban tree coverage could be an effective public-health strategy.
So the passage mainly describes a study that finds a link between tree coverage and lower anxiety and uses that to support the idea that greenery can benefit mental health.
Eliminate choices that contradict or add unsupported ideas
Now compare each answer to your summary and the passage:
- Choice A says income and age are stronger predictors than tree canopy and that Nguyen questions assumptions about greenery. The passage says she controlled for income and age and supports greenery as a strategy, so A reverses the relationships.
- Choice B says Nguyen discovered that only mature trees, not saplings, influence anxiety and that this complicates theories about plant density. The passage never compares mature trees to saplings or mentions theories about plant density, so B adds claims not in the text.
- Choice C says healthcare access, rather than tree coverage, determines anxiety, refuting urban planning claims. The passage says she controls for healthcare access and still finds a link with tree canopy; C directly contradicts the text.
These three choices conflict with or go beyond what the passage actually says, so they should be eliminated.
Confirm the remaining choice matches the passage’s main point
With A, B, and C eliminated, the remaining choice is D. Choice D says that Nguyen’s study shows a correlation between increased tree coverage and reduced anxiety and that this strengthens the argument that urban greenery benefits mental health. This exactly matches the passage’s description of her findings and her conclusion that increasing tree coverage could be an effective public-health strategy, so D is the best statement of the main idea.