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
[{'content': 'A man with gynecomastia and infertility, cause? \nSelect and explain. \nA. Digitalis, B. Omeprazole, C. Erythromycin, D. Cimetidine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Cimetidine (but not other H2 blockers) has antiandrogenic action. It displaces dihydrotestosterone from its cytoplasmic receptor. \nIt also increases plasma prolactin and inhibits degradation of estradiol by the liver. \nHigh doses given for long periods have produced gynaecomastia, loss of libido, impotence and temporary decrease in sperm count leading to infertility.', 'role': 'assistant'}]