Final answer:
A cochlear implant can restore hearing ability in people with a nonfunctional cochlea.
Step-by-step explanation:
A cochlear implant is a device that can restore hearing in people with a nonfunctional cochlea. It consists of a microphone that picks up sound, a speech processor that selects sounds in the range of human speech, and a transmitter that converts these sounds to electrical impulses. These impulses are then sent to the auditory nerve, allowing the person to perceive sound. Therefore, the correct answer to the question is C. Hearing ability.