This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
C shaped curve on tympanometry is seen in 
Select and explain. 
A. Serous otitis media, B. Otosclerosis, C. TM perforation, D. Retracted tympanic membrane
D: Retracted tympanic membrane
Answer: D: Retracted tympanic membrane 
Explanation: Type C tympanometry Maximum compliance occurs with negative pressure in excess of 100mm H2O Seen in retracted tympanic membrane and may show some fluid in middle ear. Ref: Dhingra 7e pg 27.