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
Drug which decreases efficacy of testosterone 
Select and explain. 
A. Isoniazid, B. Ketoconazole, C. Rifampicin, D. None
B: Ketoconazole
Answer: B: Ketoconazole 
Explanation: Ans. is 'b' i.e., Ketoconazole