This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
[{'content': 'Aim of mastoid surgery in CSOM which should receive first priority is: \nSelect and explain. \nA. Making the ear dry, B. Improvement in hearing, C. Preservation of hearing, D. Rendering the ear safe', 'role': 'user'}, {'content': 'Answer: D \nExplanation: CSOM is notorious for intracranial complications. The first priority in mastoid surgery is given to free drainage of pus to render the ear safe. Second priority is given to preserve or reconstruct hearing mechanism.', 'role': 'assistant'}]