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': 'Commonest cause of carcinoma endometrium is: \nSelect and explain. \nA. Unopposed estrogen, B. Multiple sex paner, C. Early marriage, D. Early menarche', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Unopposed estrogen', 'role': 'assistant'}]