**Core Concept**
Decompression of the endolymphatic sac is a surgical procedure aimed at relieving endolymphatic hydrops, a condition characterized by an abnormal accumulation of endolymph fluid in the inner ear. This procedure is primarily used to treat Meniere's disease, a disorder of the inner ear that affects balance and hearing.

**Why the Correct Answer is Right**
The correct answer is related to Meniere's disease, which is caused by an imbalance in the pressure of the endolymphatic fluid in the inner ear. Decompression of the endolymphatic sac is performed to alleviate symptoms such as vertigo, tinnitus, and hearing loss by reducing the pressure of the endolymphatic fluid. This procedure involves opening the endolymphatic sac to allow excess fluid to drain out, thereby reducing the pressure and alleviating symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because decompression of the endolymphatic sac is not a treatment for acoustic neuroma, a type of benign tumor that affects the nerve connecting the inner ear to the brain.
**Option B:** This option is incorrect because decompression of the endolymphatic sac is not a treatment for labyrinthitis, an inner ear infection that causes vertigo, hearing loss, and tinnitus.
**Option D:** This option is incorrect because decompression of the endolymphatic sac is not a treatment for otosclerosis, a type of bone growth in the middle ear that causes hearing loss.

**Clinical Pearl / High-Yield Fact**
Meniere's disease is characterized by a triad of symptoms: vertigo, tinnitus, and hearing loss. The disease is often associated with an abnormality in the inner ear, specifically the endolymphatic sac, which is responsible for regulating the pressure of the endolymph fluid.

**Correct Answer: C**.