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': 'Percentage of pheochromocytoma that are bilateral is: \nSelect and explain. \nA. <1%, B. 1-5%, C. 10%, D. 25%', 'role': 'user'}, {'content': "Answer: C \nExplanation: Pheochromocytomas often are called the 10 percent tumor because 10% are bilateral, 10% are malignant, 10% occur in pediatric patients, 10% are extra-adrenal, and 10% are familial. Ref: Schwaz's principle of surgery 9th edition, chapter 38.", 'role': 'assistant'}]