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 'C' tympanogram is seen in 
Select and explain. 
A. Serous Otitis media, B. Otosclerosis, C. Ossiullor discontinuity, D. Eustachian Tube blockade
D: Eustachian Tube blockade
Answer: D: Eustachian Tube blockade 
Explanation: None