Answer: c. conduction deafness
Step-by-step explanation:
Conductive deafness is an obstruction or alteration in the transmission of sound into the tympanic membrane or inside the ossicles of middle ear. Person is not able to hear the sound from external stimuli. One of the reason of conduction deafness is otosclerosis.
Otosclerosis is a medical problem in which the abnormal growth of bone in the middle ear or fusion of the bones of ear ossicles occurs. This abnormal growth or fusion prevents the ear from working properly and it is responsible for hearing loss.