A Young Couple Has Had Regular,unprotected Sexual Intercourse for 4

A young couple has had regular,unprotected sexual intercourse for 4 years,without a pregnancy.They are seeking help at an assisted reproduction/in vitro fertilization clinic for infertility.The husband is very serious about weight training and physical fitness.Semen analysis reveals a sperm count of 7 million/mL (i.e.,very low) .His blood analysis reveals an elevated testosterone level.The psychiatrist at the clinic suspects that the husband injects (i.e.,abuses) testosterone,which turns out to be true.The husband has read online that testosterone stimulates spermatogenesis,and so he is confused as to why he has a low sperm count.How is this explained?

A) Injected testosterone must first be converted to dihydrotestosterone (DHT) in the testes.
B) High levels of injected testosterone are toxic to sperm.
C) Injected testosterone increases levels of sex hormone-binding globulin (SHBG) ,thereby reducing the level of "free" testosterone.
D) Injected testosterone inhibits intratesticular production of testosterone through negative feedback on luteinizing hormone (LH) .
E) Injected testosterone increases levels of circulating estrogen,which inhibits spermatogenesis.