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: Surgery
Which is the most common cause of male infertility 
Select and explain. 
A. Smoking, B. Varicocele, C. Epididymitis, D. Idiopathic
B: Varicocele
Answer: B: Varicocele 
Explanation: Varicocele is the most common cause of male infertility.