Thanks for your feedback about the exam interface! It's great to hear that you've been finding it helpful, and thank you for the note about the timer -- I'll bring that to the attention of our tech team.
Re: this question, the basic issue is that the Q tells us that the kinetic chain is uncoupled at the hips, so we wouldn't expect it to affect the shoulders (or at least we can't make any real predictions about how it would be transferred from the hips to elsewhere in the body). Although the hips/shoulder distinction is the key problem with choice A, it's also generally a good idea to pick answers that focus directly on what we can conclude from the data we're given w/ minimal additional steps. Predicting that less input energy = less velocity is pretty straightforward, and doesn't require as much of a leap as you would have to make to predict injury likelihood. Hope this clarifies things and best of luck as you keep studying!!