Progressive deafness of the ear that is caused by a hardening condition is known as:

A) fenestration.
B) otomycosis.
C) Ménière's disease.
D) otosclerosis.

Otosclerosis is a condition that causes the progressive deafness of the ear due to the hardening of the middle ear bones. Fenestration is a surgical procedure that creates an opening in the ear for the purpose of improving hearing. Otomycosis is a fungal infection in the ear canal. Ménière's disease is a condition that causes vertigo, ringing in the ears, and hearing loss.