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
Type Ad curve is seen in - 
Select and explain. 
A. Eustachian tube obstruction, B. After stapedectomy, C. Middle ear tumours, D. Secretory otitis media
B: After stapedectomy
Answer: B: After stapedectomy 
Explanation: Ans. is 'b' i.e., After stapedectomy