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: Unknown
[{'content': 'In sipple syndrome [MEN II ) all are present except: \nSelect and explain. \nA. Pheochromocytoma, B. Pituitary hyperplasia, C. Medullary carcinoma thyroid, D. Parathyroid hyperplasia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b (Pituitary hyperplasia) Ref: Robbins, 7th ed,p. 222MEN 2a is characterized by pheochromocytoma, medullary carcinoma thyroid, and Parathyroid hyperplasia SYNDROMES MEN IMEN IIAMEN II BPituitaryParathyroidAdenomaHyperplasiaAdenomaCarcinomaHyperplasia Adrenal thyroidCortical hyperplasiaPheochromocytomaC cell hyperplasiaMedullary carcinomaPheochromocytomaC cell hyperplasiaMedullary carcinomaExtra endocrine changes MucocutaneousGanglioneuromaMarfanoid habitusMutant geneMEN IRETRETHirschsprung disease - loss of function in RET proto-oncogeneMEN IIA - a gain of function in RET proto-oncogene', 'role': 'assistant'}]