Answer:
d. tympanic membrane
Explanation:
The external auditory canal is the communication channel between the ear pinna and the middle ear. It can be divided into two regions, one outermost and one innermost. The outermost region is of cartilaginous consistency and is covered by very fine hair and glands that secrete the earwax, a sticky yellow substance that acts to retain dust and microorganisms. The innermost region is of bone consistency and is housed in the temporal bone, one of the skull bones. The external auditory canal ends in a membrane called the tympanic membrane.
