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': 'A-30-year old male is having Attic cholesteatoma of left ear with lateral sinus thromboplebitis. Which of the following will be the operation of choice - \nSelect and explain. \nA. Intact canal will be the operation of choice, B. Simple mastoidectomy with tympanoplasty, C. Canal wall down mastoidectomy, D. Mastoididectomy with cavity obliteration', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]