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': 'Association of carcinoma gall bladder with gall stones is about - \nSelect and explain. \nA. 50%, B. 70%, C. 90%, D. 20%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]