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': 'False about medullary Cancer thyroid is? \nSelect and explain. \nA. Tumor marker is calcitonin, B. From parafollicular cells, C. RET mutation, D. 90% familial', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 90% of medullary carcinoma thyroid is sporadic.', 'role': 'assistant'}]