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': 'Cholestatoma is usually present at: \nSelect and explain. \nA. Anteroinferior quadrant of tympanic membrane, B. Posteroinferior quadrant of tympanic membrane, C. Attic region, D. Cental part', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Atticoantral type or marginal or unsafe otitis media involves posterosuperior part of middle ear cleft (attic, antrum, posterior tympanum and mastoid) and is associated with cholesteatoma.', 'role': 'assistant'}]