Final answer:
The conversion of vibrations into sound sensations is completed in the (C) cochlea of the inner ear, where mechanical vibrations are translated into neural signals.
Step-by-step explanation:
The final step required to convert vibrations into sound sensations takes place in the cochlea, which is part of the inner ear. Auditory stimuli, like sound waves, reach the outer ear and cause the tympanum to vibrate. These vibrations are then transmitted through the middle ear by the ossicles - the malleus, incus, and stapes.
The stapes, the smallest of these bones, passes the vibrations to the oval window of the cochlea. Inside the cochlea, the mechanical energy causes the basilar membrane to flex, which bends the stereocilia on receptor hair cells. This bending of stereocilia triggers the hair cells to send auditory neural signals to the brain, ultimately creating the sensation of sound.