Explanation
Correct answer: B.
Choice B is the best answer. The lighter bars show what happened when the announcement was to come before the election, and the darker bars show what happened when the announcement was to come after the election. For all three of the outcomes, the light and dark bars are virtually the same, demonstrating that the announcement timing didn't actually make a difference.
Why the other choices are wrong
Choice A
Choice A is incorrect. This accurately describes some data from the graph, but it doesn’t weaken the hypothesis. It doesn’t include the “announcement after election” data for comparison.
Choice C
Choice C is incorrect. This accurately describes some data from the graph, but it doesn’t weaken the hypothesis. It doesn’t include the “announcement after election” data for comparison.
Choice D
Choice D is incorrect. This accurately describes some data from the graph, but it doesn’t weaken the hypothesis. It doesn’t include the “announcement before election” data for comparison.