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: Medicine
[{'content': "Weight gain occurs in all, except : \nSelect and explain. \nA. Pheochromocytoma, B. Cushing's syndrome, C. Hypothyroidism, D. Insulin secreting tumor", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Pheochromocytoma): Pheochromocytoma causes weight loss.', 'role': 'assistant'}]