**Core Concept**
The vestibular system is responsible for detecting linear acceleration and changes in head position. The otolith organs, specifically the utricle and saccule, are sensitive to linear acceleration in the horizontal and vertical planes.

**Why the Correct Answer is Right**
The utricle is responsible for detecting horizontal linear acceleration, which is perceived as a change in head position. This is achieved through the movement of otolith particles in the fluid of the utricle, activating hair cells. The vestibular nerve then transmits this information to the brain, allowing for the perception of horizontal acceleration. The utricle is also sensitive to changes in head position in the sagittal plane.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the saccule is primarily responsible for detecting vertical linear acceleration, not horizontal acceleration.
* **Option B:** This option is incorrect because the semicircular canals are responsible for detecting rotational acceleration, not linear acceleration.
* **Option D:** This option is incorrect because the cochlea is responsible for sound processing and hearing, not vestibular function.

**Clinical Pearl / High-Yield Fact**
The vestibular system plays a crucial role in maintaining balance and spatial orientation. Damage to the vestibular system can result in symptoms such as vertigo, dizziness, and nystagmus.

**Correct Answer: C. The utricle**