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': "A chronic smoker presented with mild haemoptysis. He also gave a history of hypeension and obesity. Lab data showed raised ACTH levels, which were not suppressed by high dose dexamethasone. The cause for the Cushing's syndrome in 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: Answer is D (Ectopic ACTH secreting tumor) : Raised ACTH levels not suppressible by high dose dexamethosone in the backdrop of chronic smoking and hemoptysis lead us to a diagnosis of ectopic ACTH secretion from a bronchogenic carcinoma.', 'role': 'assistant'}]