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': 'Which of the following is true about Nelson syndrome \nSelect and explain. \nA. Occurs after adrenalectomy, B. Pituitary harmones are decreased, C. Hyper pigmentation, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: After bilateral adrenalectomy due to increased ACTH levels hyper pigmentation is seen. Pituitary tumor enlargement along with low pituitary harmones is present.', 'role': 'assistant'}]