**Core Concept:** A cochlear implant is a surgical procedure to restore hearing in individuals with severe to profound sensorineural hearing loss. It involves implanting an electronic device that bypasses damaged parts of the auditory system and stimulates the cochlea or auditory nerve.

**Why the Correct Answer is Right:**

Correct Answer: C. Electrode array

The electrode array is placed during surgery for a cochlear implant to directly stimulate the auditory nerve fibers in the cochlea. It consists of a series of electrodes that are inserted into the cochlea, bypassing the damaged inner ear structures and providing electrical stimulation to the auditory nerve fibers. This creates a sense of sound in the patient.

**Why Each Wrong Option is Incorrect:**

A. **Electrode array (incorrect answer text):** This option is incorrect because the electrode array is the correct answer, not one of the other options.

B. **Cochlear stimulator:** A cochlear stimulator is not the correct term for the device placed during surgery. The correct term is cochlear implant, as explained above.

D. **Auditory nerve:** While the auditory nerve is a part of the auditory pathway, placing the auditory nerve as a surgical option is incorrect because the electrode array is inserted into the cochlea for stimulation, not the auditory nerve itself.

**Clinical Pearl:** The cochlear implant is a vital tool for restoring hearing in individuals with severe to profound sensorineural hearing loss. Understanding the surgical procedure, including the placement of the electrode array, is essential for understanding the implant's functional mechanism and its impact on the patient's auditory perception.