This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which one of the following agents inhibits spermatogenesis ? 
Select and explain. 
A. Gelusil, B. Gemcadiol, C. Gestodene, D. Gossypol
D: Gossypol
Answer: D: Gossypol 
Explanation: None