**Core Concept**
Cold water irrigation of the ears is a technique used to assess the function of the vestibular system, specifically the vestibulo-ocular reflex (VOR). This reflex helps maintain balance and eye movement during head movements. The response to cold water irrigation is a clinical indicator of vestibular function.

**Why the Correct Answer is Right**
When cold water is irrigated into the ear, the stapes bone is stimulated, triggering the vestibular apparatus in the inner ear. This stimulation activates the vestibular nerve and sends signals to the brain, which then responds by causing nystagmus (involuntary eye movement). The direction of the nystagmus is away from the irrigated ear, indicating a normal vestibular response. This response is seen in patients with a functioning vestibular system.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because cold water irrigation does not stimulate the cochlea, which is responsible for sound processing. The response to cold water irrigation is not related to hearing.
**Option B:** This option is incorrect because the response to cold water irrigation is not related to the otolith organs (utricle and saccule), which are responsible for detecting linear acceleration and deceleration.
**Option C:** This option is incorrect because the response to cold water irrigation is not related to the semicircular canals, which are responsible for detecting rotational movements.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the response to cold water irrigation is a sensitive indicator of vestibular function, and any abnormal response can indicate a vestibular disorder.

**Correct Answer: C. Normal vestibular function.**