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': 'A 20 year old male presents with chronic constipation, headache and palpitations. On examination he had marfanoid habitus, neuromas of tongue, medullated corneal nerve fibers and nodule of 2 x 2 cm size in It lobe of thyriod. This pt. is a case of - \nSelect and explain. \nA. Sporadic medullary carcinoma of thyroid, B. Familial medullary carcinoma of thyroid, C. MEN IIA, D. MEN IIB', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]