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
Bing test is 
Select and explain. 
A. Audiometric test, B. Air conduction test, C. Bone conduction test, D. Special test
C: Bone conduction test
Answer: C: Bone conduction test 
Explanation: Bing test: It is a test of bone conduction Examines the effect of occlusion of ear canal on the hearing. A vibrating tuning fork is placed on the mastoid while the examiner alternately closes and opens the ear canal by pressing on the tragus inwards. A normal person or one with sensorineural hearing loss hear louder when the ear canal is occluded and softer when the canal is open (Bing positive). A patient with conductive hearing loss will appreciate no change (Bing negative). Ref: Dhingra; 6th Edition; pg no 22