Drug use can cause the spread of diseases.

Yes, drug use can cause the spread of diseases, particularly drugs that involve injections. Drug users usually have sessions with other drug users and tend to use the same paraphernalia that the other is using. The most common disease in drug use is HIV or AIDS. This occurs when direct contact with an infected blood is transferred to another by means of injections. Drug users are at a high risk of contracting this disease and might also easily pass it to others through sexual intercourse. 

(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!