This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
[{'content': 'All of the following are features of MEN IIb, except - \nSelect and explain. \nA. Pituitary tumor, B. Pheochromocytoma, C. Medullary carcinoma thyroid, D. Neuromas', 'role': 'user'}, {'content': "Answer: A \nExplanation: MEN 2A is characterised by Medullary Thyroid Carcinoma (90%), Pheochromocytoma (>50%) and Parathyroid adenoma (10-25%).MEN 2B (also known as MEN 3) is characterised by MTC (>90%), Pheochromocytoma (>50%) and associated abnormalities (40-50%) - mucosal neuromas, marfanoid habitus, medullated corneal nerve fibres, megacolon. Reference : page 2336 Harrison's Principles of Internal Medicine 19th edition", 'role': 'assistant'}]