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': 'Schwartz operation is done in - \nSelect and explain. \nA. CSOM, B. Serous otitis media, C. Otosclerosis, D. Acute mastoiditis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Indications of simple / cortical mastoidectomy (Schwartz operation)\n\nAcute coalescent mastoiditis.\nIncompletely resolved acute otitis media with reservoir sign.\nMasked mastoiditis.\nAs a initial step to perform:\n\n\nEndolymphatic sac surgery\nDecompression of facial nerve\nTranslabyrinthine or retrolabyrinthine procedures for acoustic neuroma.', 'role': 'assistant'}]