Specificity is the answer. You are targeting a certain muscle in your body to improve it for an upcoming sport or activity like running a marathon or entering a Mr.Olympian body-building competition.
The correct answer is D. Avoiding high-risk situations
A could lead to a possible sexual encounter. B would just lead to confrontation. C is just dumb and would lead to potentially putting yourself in harms way.
If you avoid high risk situations where the chances of a sexual encounter are high you are more than likely able to successfully remain abstinent.
I think the answer is C because many teens and adults have unsafe lifestyles that lead to injury and death.
Go for longer reps each day then rest and it will improve your lower body strength.