A 2023 study compared four cities' bicycle injury rates (per million bike-trips): City J, 12; K, 8; L, 18; M, 20. The study also reported each city's bike-lane mileage and helmet-law strictness, varying both: City J, high lanes + lax helmet law; K, high lanes + strict helmet; L, low lanes + lax; M, low lanes + strict. The researchers argued that bike-lane infrastructure—not helmet laws—drives differences in injury rates. The strongest data support is ______
Which choice most logically completes the text using the data above?
- Acheck_circle
the comparison J vs. K (both high lanes: 12 vs. 8) and L vs. M (both low lanes: 18 vs. 20)—helmet law alone changes rates by only 2-4 points, while lane access changes them by ~10 points.
- B
the average rate across cities.
- C
City K's lowest injury rate of 8.
- D
City M's highest injury rate of 20.
Explanation
"Lanes drive differences, not helmets" requires comparing the within-lane helmet effect to the within-helmet lane effect. Choice B does both comparisons and shows lanes matter much more than helmet laws.