D. Give performers an unfair advantage
Let’s talk about option A; Drugs that athletes take (for e.g. steroids) they INCREASE athletes muscle mass & endurance. They look bigger & muscular than a normal natural athlete.
Option B is also incorrect because there is no drugs that are legal in sports
Option C - It increase the athletes performance and your extremely energetic. You are doing what an natural cannot do in a short period of time.
SO OPTION D - It’s unfair to the natural ones