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': 'Cortical mastoidectomy is indicated in - \nSelect and explain. \nA. Cholesteatoma without complication, B. Coalescent mastoiditis, C. CSOM with brain abscess, D. Perforation in Pars flaccida', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]