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
Communication between middle ear and Eustachian tube is obliterated in which surgery? 
Select and explain. 
A. Tympanoplasty, B. Schwaz operation, C. Modified radical mastoidectomy, D. Radical mastoidectomy
D: Radical mastoidectomy
Answer: D: Radical mastoidectomy 
Explanation: In radical mastoidectomy, the opening of Eustachian tube is closed by curetting its mucosa and plugging the opening with tensor tympani muscle or cailage.