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': 'In azoospermia, the diagnostic test which can distinguish between testicular failure and obstruction of Vas deferens is: \nSelect and explain. \nA. Estimation of FSH level, B. Estimation of testosterone level, C. Karyotyping, D. FNAC of testes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: As discussed in the preceding text: estimation of the levels of FSH can differentiate between pretesticular, testicular and posttesticular causes of male infertility.', 'role': 'assistant'}]