Answer
Statement "d" does not correctly describe the way in which the spiral organ functions.
It is not the outer hair cells ,but the inner hair cells ( stereocilia) of the spiral organ that are chiefly responsible for our perception of sound.
Work Step by Step
The spiral organ has three types of cells; supporting cells, and two types of hair cells ( stereocilia) --outer hair cells and inner, less numerous, hair cells.
Most of the afferent nerve fibers in the spiral organ coil around inner hair cells. As a consequence the inner hair cell are mainly responsible for our perception of sound. The outer hair cells are in contact mainly with efferent nerve fibers from the brain. The function of the outer hair cells is two-fold: they increase the sensitivity of the inner hair cells by amplifying the motion of the basilar membrane; also, as part of a negative feedback loop, they also protect the inner stereocilia from damage by dampening the responses of the basilar membrane to very loud sounds.
