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: Pathology
[{'content': 'In which of the following is medullary thyroid cancer is the most aggressive form - \nSelect and explain. \nA. MEN type I, B. MEN type II a, C. MEN type II b, D. Sporadic cases', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Medullary thyroid carcinoma in MEN 2B develops earlier and is more aggressive than in MEN 2A.', 'role': 'assistant'}]