Which foods have been shown to reduce the risks of many chronic diseases, such as cardiovascular disease, cancer, and diabetes?
a. whole dairy products
b. foods that contain trans fat
c. whole grains
d. protein foods

I believe the answer is whole grains. They help reduce disease.
Protein also helps, but only if it is lean cuts.

So I’d say C. Whole grains

(a) is not correct because one does not get increased cholesterol  from lifting weights.(b) is not correct because lifting weights cannot reduce the risk of a hereditary disease.(c) is not correct because back pain isn't a benefit! and plus, if he lifts weights properly, he should not have back pain.(d) is the correct answer because his ligaments will gain mass, making it easier for him to carry heavier weights and he will also be stronger!