This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
[{'content': 'Commonest cause of Cushing syndrome is \nSelect and explain. \nA. Adrenal adenoma, B. Carcinoma, C. Atrophy, D. Hyperplasia', 'role': 'user'}, {'content': "Answer: D \nExplanation: MC cause of Cushing's syndrome is iatrogenic exogenous administration of steroids. MC endogenous cause of Cushing's syndrome is bilateral adrenal hyperplasia secondary to hypersecretion of ACTH from pituitary or from an ectopic non-pituitary source", 'role': 'assistant'}]