A 16-year-old boy who is the backup quarterback for the local high school team is in your office complaining of worsening acne. For the last few months, he has noted more acne and more oily hair. On his examination, you note gynecomastia and small testicular volume. He is SMR 5. Which of the following drugs of abuse is the likely explanation for all of his findings?
a) Marijuana
b) Cocaine
c) Anabolic steroids
d) Opioids