A 2018 study examined whether the introduction of a public bike-share system in a city was associated with reduced car traffic. Researchers reported daily car trips (in millions) for the central district before and after the system launched, alongside the same data for a comparable nearby district that did not adopt bike share. Central district: 2.4 (before), 2.1 (after); Comparison district: 2.6 (before), 2.3 (after). The researchers concluded that bike share was not the cause of the central district's traffic decline. The data point most uniquely supporting this conclusion is ______
Which choice most logically completes the text using the data above?
- A
the absolute level of car trips in both districts.
- B
the central district's higher post-launch trip count than the comparison district's pre-launch count.
- C
the central district's 0.3-million decline after launch.
- Dcheck_circle
the comparison district's similar 0.3-million decline despite no bike share.
Explanation
To argue bike share didn't cause the decline, one needs evidence that comparable areas without bike share saw the same change. Choice B provides exactly this counterfactual: the comparison district dropped equally without any intervention, undermining a causal claim for bike share.