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': 'Commonest complication of CSOM is \nSelect and explain. \nA. Subperiosteal abscess, B. Mastoiditis, C. Brain abscess, D. Meningitis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 50% of brain abscesses in adults and 25% in children are otogenic in origin. In adults, an abscess usually follows CSOM with cholesteatoma. (Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 90)', 'role': 'assistant'}]