A 2023 study compared four cities' library usage rates along with two factors: median income (high/low) and library hours (long/short): City A, high income + long hours, 64% of adults using; B, high income + short hours, 51%; C, low income + long hours, 58%; D, low income + short hours, 42%. The researchers concluded that long library hours boost usage by a similar percentage in both income groups. The strongest support is ______
Which choice most logically completes the text using the data above?
- A
City D's lowest rate of 42%.
- Bcheck_circle
the within-income contrasts: A vs. B (high income: +13 points) and C vs. D (low income: +16 points)—long hours add a similar number of points in both groups.
- C
the average across cities.
- D
City A's highest rate of 64%.
Explanation
"Similar percentage boost in both income groups" requires comparing long-hour effect within each income stratum. Choice B captures the 13 vs. 16 point similarity, supporting the claim.