Many sports injury can be prevented by all the following except : a. stretching only before a workout b. warming and cooling down c. wearing the safety equipment d. avoiding over-training

I would say "avoid over-training". I would say that this would most likely be the correct answer due to the fact that over working your body would be putting your body under too much work that you can really handle. And as you do that, when the real game happens, you could have to sore bones, and thus, this would then lead to an injury.

The answer would be a (carbohydrates)