Question

gelatinous structure in the cochlea containing the hair cells that serve as auditory receptors

organ of corti
coelom of corti
ampulla of corti
gonad of corti
testis of corti

Explanation:

The organ of Corti is a structure in the cochlea that contains hair cells which act as auditory receptors. The other options are incorrect terms. Coelom refers to a body cavity, ampulla is a different anatomical structure (e.g., in the ear's semicircular canals but not related here), gonad is a reproductive gland, and testis is a male gonad.

Answer:

organ of Corti