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
A -30-yead old male is having Attic cholesteatoma of left ear with lateral sinus thromboplebitis. Which of the following will be the operation of choice? 
Select and explain. 
A. Intact canal will be the operation of choice, B. Simple mastoidectomy with Tympanoplasty, C. Canal wall down mastoidectomy, D. Mastodidectomy with cavity obliteration
C: Canal wall down mastoidectomy
Answer: C: Canal wall down mastoidectomy 
Explanation: In Attic cholesteatoma, if it invades eustachian tube or perilabyrynthine tissue, then management is Radial Mastoidectomy.