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: Psychiatry
[{'content': 'How to differentiate between psychological and organic erectile dysfunction ? \nSelect and explain. \nA. Nocturnal penile tumescence, B. PIPE therapy, C. Sildenafil induced erection, D. Squeeze technique', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. Nocturnal penile tumescenceOne of the impoant method to distinguish psychogenic impotence from organic imPotence is nocturnal penile tumsescence & early morning erection which are preserved in psychogenic impotence but not in organic cause of impotence.', 'role': 'assistant'}]