Gym owner: Many injuries are caused by wearing shoes that are not

Official Explanation:

(C) is correct. If runners take advantage of all the gym programs, that would include the side-to-side motion activities that warrant the recommended cross-trainers.

(A) mentions other activities with side-to-side motion. That suggests there are other reasons to get a second set of sneakers, but it still assumes runners would participate in those sports. If they don't, then there is still no reason for them to get an extra pair of sneakers.

(B) is irrelevant. The argument is based on the motion of the foot, not how much cushioning the shoe provides. Even if this were true, there's no suggestion that runners would need both types of shoe.

(D) is irrelevant. What other people do offers no support for whether runners should do the same.

(E) may be tempting, but it is also irrelevant to the argument. Even if proper shoes are the most important factor in preventing injuries, there's still no evidence that runners are participating in the activities with side-to-side motion that would warrant the purchase of a second pair of sneakers. Perhaps they already own the proper footwear for running and don't do any other exercise.