The main role of in supporting physical activity is to serve as an antioxidant, protecting tissues from oxidation.â

I think the correct term to fill in the blank would be Vitamin E. The main role of Vitamin E in supporting physical activity is to serve as an antioxidant, protecting tissues from oxidation. This vitamin is an antioxidant and is important in having strong immunity and healthy skin. It acts a peroxyl radical scavenger which disables the production of free radicals in the tissues which are damaging to the body. It reacts with the free radical and forms a tocopheryl radical which is reduced by a hydrogen donor. Therefore, returning it to the reduced state. Free radicals are harmful to the cells, organs and the tissues. 

C) reflection (i also looked up the other choices just to make sure)