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: Surgery
[{'content': 'Gall stones - \nSelect and explain. \nA. Are about twice as common in men as in women, B. There is an increased incidence of stones in diabetics, C. About 80-90% of gall stones are radio-opaque, D. Are usually more than 50 mm in diameter', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e. There is an increased incidence of stones in diabetics", 'role': 'assistant'}]