Final answer:
The electrical potential necessary for hearing is primarily caused by the depolarization of auditory hair cells in the cochlea. This is due to the bending of stereocilia on the hair cells when sound-induced fluid waves move through the cochlea, which then leads to the generation of nerve impulses that the brain interprets as sound.
Step-by-step explanation:
The electrical potential that leads to hearing is caused by the depolarization of auditory hair cells within the cochlea. When sound waves travel through the ear, they cause the fluid inside the cochlea to move. This movement results in the bending of the stereocilia attached to the top of the hair cells, which are embedded in the basilar membrane. As the stereocilia bend, they open mechanically gated ion channels that cause the hair cells to depolarize. This depolarization leads to the release of neurotransmitters that elicit the generation of nerve impulses or action potentials within the auditory nerve fibers. Those nerve impulses are then sent to the brain, where they are interpreted as sound.
The process begins with sound waves reaching the tympanic membrane and causing vibrations, which are transmitted through the middle ear bones (ossicles) to the cochlea. However, it is the actual bending of the hair cells that leads to the creation of electrical signals which the brain can interpret. Therefore, the correct answer to the question of what actually causes the electrical potential to be formed is c) Auditory hair cells depolarization.