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: Medicine
[{'content': 'The most common cause of Cushing&;s syndrome is: \nSelect and explain. \nA. Pituitary adenoma, B. Adrenal adenoma, C. Ectopic ACTH, D. Iatrogenic steroids', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The most common cause of Cushing&;s syndrome is Iatrogenic administration of steroids for a variety of reasons." REF: Harrison book of internal medicine 21ST EDITION', 'role': 'assistant'}]