A recent paper claims that cities with extensive bicycle infrastructure show lower rates of cardiovascular disease among residents. The authors interpret this correlation as evidence that biking improves health. A different reading is possible: residents already inclined toward exercise may simply choose to live in such cities, producing the correlation without any causal effect of the infrastructure itself.
Which choice best describes the function of the third sentence in the text?
- Acheck_circle
It offers a selection-based alternative explanation that complicates the causal interpretation.
- B
It restates the authors' claim using different terms.
- C
It introduces a new study unrelated to the cardiovascular finding.
- D
It directly supports the authors' causal interpretation.
Explanation
The third sentence proposes that self-selection, not infrastructure, may produce the correlation. B captures the alternative-explanation function.