A student is writing an essay arguing that urban green spaces improve mental health outcomes. She has found the following two sources:
Source 1: A longitudinal study tracking 4,200 urban residents over ten years found that participants living within 300 meters of a park reported 18% lower rates of anxiety disorders compared to those living farther away, even after controlling for income and age.
Source 2: A urban planning report notes that cities investing in green infrastructure—parks, community gardens, and tree canopies—see measurable reductions in heat island effects and noise pollution, both of which are established stressors linked to diminished psychological well-being.
Which of the following most effectively synthesizes both sources to support the student's central argument?
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A
Urban green spaces benefit residents both directly, through proximity effects that measurably reduce anxiety disorders, and indirectly, by mitigating environmental stressors like heat and noise that contribute to poor mental health.
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B
Longitudinal studies are more reliable than urban planning reports, so the 18% reduction in anxiety disorders is the strongest evidence for the student's argument.
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C
Cities should invest in green infrastructure primarily to reduce heat island effects, which will then incidentally improve the mental health of nearby residents.
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D
Because both sources discuss urban environments, they collectively suggest that location—rather than green space itself—is the primary factor in mental health outcomes.