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: Gynaecology & Obstetrics
[{'content': "A male with azoospermia. On examination size of testis normal FSH normal testosterone normal. Most probable cause is \nSelect and explain. \nA. MAL descended testis, B. Klinefelter's syndrome, C. Kallmann's syndrome, D. VAS obstruction", 'role': 'user'}, {'content': 'Answer: D \nExplanation: A normal level of FSH in azoospermia suggests an obstructive lesion in the vas or epididymis. \nHigh FSH may indicate primary gonadal failure.', 'role': 'assistant'}]