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
In Bing test on alternately compressing and relaxing the tragus the sound increases and decreases. This indicates: 
Select and explain. 
A. SN deafness, B. Adhesive otitis media, C. Otosclerosis, D. CSOM
A: SN deafness
Answer: A: SN deafness 
Explanation: (a) SN deafness(Ref. Scott Brown, 8th ed., Vol 2; 927)The other options being conductive pathologies so show no change in hearing.