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 causing gynecomastia is : 
Select and explain. 
A. Spironolactone, B. Rifampicin, C. Penicillin, D. Bumetanide
A: Spironolactone
Answer: A: Spironolactone 
Explanation: None