I got this wrong when taking the pt, but I think I can make sense of this. The first sentence of the stimulus says that "many" dinosaurs were becoming extinct when the asteroid hit. The next sentence states that the asteroid was "PROBABLY not responsible for MOST of the dinosaur extin...

When I read the stimulus, I thought the parenthetical statement was referring to the idea that the belief was indeed becoming widespread, not that the belief is in fact true. That's why I picked D. Guess I need to read more carefully.