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
All of the following will produce conductive hearing loss, Except - 
Select and explain. 
A. Otosclerosis, B. Serous otitis media, C. Endolymphatics Hydrops, D. Suppurative otitis media
C: Endolymphatics Hydrops
Answer: C: Endolymphatics Hydrops 
Explanation: None