Explanation
Correct answer: D.
Choice D is the best answer. The passage tells us that participants were “more than seven times likelier to characterize the modified songs as having swing than to characterize the original versions as having swing.” Because the modified songs had been changed by altering the timing of the downbeats and offbeats, this suggests that the timing of downbeats and offbeats may play a crucial role in giving a song swing.
Why the other choices are wrong
Choice A
Choice A is incorrect. Although the passage mentions that the researchers “synchronized the offbeats” in the modified songs, they also “delayed the downbeats” in those songs. Because we can’t disentangle whether it was the synchronized offbeats, the delayed downbeats, or the combination of both that increased the song’s swing, we don’t have enough information to make this inference.
Choice B
Choice B is incorrect. The passage doesn’t mention whether or not it’s difficult for a jazz musician to give a song swing, so there’s no basis for this inference.
Choice C
Choice C is incorrect. The passage doesn’t compare jazz songs that feature piano to those that don’t, so there’s no basis for this inference.