This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gallbladder, Subject name: Surgery
[{'content': 'Percentage of gallstones which are radiopaque: \nSelect and explain. \nA. 10%, B. 20%, C. 30%, D. 40%', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most (90%) gallstones are radioluscent. Most (90%) kidney stones are radiopaque. Most gall stones are cholesterol stones (>90%) are radiolucent', 'role': 'assistant'}]