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': "In a chronic smoker with mild haemoptysis. He also gave a history of hypeension and obesity. Lab data showed raised ACTH levels, which were not suppressed by dexamethasone. The cause for the Cushing's syndrome ha the patient is - \nSelect and explain. \nA. MEN I, B. Pituitary adenoma, C. Adrenal coical adenoma, D. Ectopic ACTH secreting tumor", 'role': 'user'}, {'content': 'Answer: D \nExplanation: ectopic ACTH production is not suppressed by high dose of dexamethasone (Harrison 17 pg 2256)', 'role': 'assistant'}]