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: ENT
[{'content': 'Simple mastoidectomy is done for - \nSelect and explain. \nA. Lateral sinus thrombophlebitis, B. Small localized cholesteatoma, C. ASOM, D. Acute mastoiditis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]