A 2022 study analyzed voter turnout in four countries that recently changed their voting laws. For each, researchers reported turnout in two consecutive elections, before and after the law change: Country A, 64% then 71%; Country B, 60% then 62%; Country C, 70% then 69%; Country D, 55% then 73%. They also reported turnout changes in <em>neighboring countries with no law change</em> over the same period: Country A's neighbor, 60% then 68%; Country B's neighbor, 58% then 60%; Country C's neighbor, 71% then 71%; Country D's neighbor, 56% then 60%. The researchers concluded that the new laws had a real causal effect only in some countries. The data most uniquely supporting a real causal effect in Country D is ______
Which choice most logically completes the text using the data above?
- A
Country D's pre-law turnout of 55%.
- B
the average turnout across all four countries.
- Ccheck_circle
Country D's 18-point post-law jump (55% → 73%) compared to its neighbor's modest 4-point increase (56% → 60%).
- D
Country D's post-law turnout of 73%.
Explanation
A "real causal effect" claim requires showing the change exceeds what comparable jurisdictions experienced over the same period. Choice B captures this counterfactual contrast—Country D's 18-point jump vs. its neighbor's 4-point increase—uniquely supporting causal attribution.