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
[{'content': 'In Bing test on alternately compressing and relaxing the tragus the sound increases and decreases. This indicates: \nSelect and explain. \nA. SN deafness, B. Adhesive otitis media, C. Otosclerosis, D. CSOM', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (a) SN deafness(Ref. Scott Brown, 8th ed., Vol 2; 927)The other options being conductive pathologies so show no change in hearing.', 'role': 'assistant'}]