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: Medicine
A 30-year old male complains of loss of erection; he has low testosterone and high prolacting level in blood; What is the likely diagnosis - 
Select and explain. 
A. Pituitary adenoma, B. Testicular failure, C. Craniopharyngioma, D. Cushing's syndrome
A: Pituitary adenoma
Answer: A: Pituitary adenoma 
Explanation: None