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
Primary receptor cells of hearing are 
Select and explain. 
A. Suppoing cells, B. Tectorial membrance, C. Tunnel of coi, D. Hair cells
D: Hair cells
Answer: D: Hair cells 
Explanation: Hair cells are impoant receptor cells of hearing. Inner hair cells are more impoant in the transmission of auditory impulses. Outer hair cells mainly receive efferent innervation from the olivary complex and are concerned with modulating the function of inner hair cells. (Ref: Diseases of EAR, NOSE and THROAT by PL Dhingra; 6th edition; page no.13)