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': 'Most common cause of erectile dysfunction: \nSelect and explain. \nA. Psychological, B. Drug induced, C. Alcohol, D. Diabetes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. PsychologicalThe most common cause of erectile dysfunction inYoung and middle-aged men: Psychological Older men: Organic (atherosclerosis)Overall: Organic (atherosclerosis)', 'role': 'assistant'}]