Question

what is a? hammer (malleus) stirrups (stapes) tympanic membrane (eardrum) cochlea

Explanation:

The tympanic membrane (eardrum) is a thin membrane that separates the outer ear from the middle ear. In the diagram, the position of label A corresponds to the location of the eardrum. The hammer (malleus), stirrups (stapes) are middle - ear bones (ossicles), and the cochlea is part of the inner ear.

Answer:

tympanic membrane (eardrum)