**Core Concept**
In Meniere's disease, the inner ear's endolymphatic system is affected, leading to an accumulation of endolymph. This results in increased pressure and fluid volume within the inner ear, causing symptoms like vertigo, tinnitus, and hearing loss.

**Why the Correct Answer is Right**
The use of vasodilators in Meniere's disease is based on the principle of increasing endolymph reabsorption. By dilating the blood vessels in the inner ear, vasodilators enhance the reabsorption of endolymph through the endolymphatic sac, thereby reducing the fluid volume and pressure within the inner ear. This helps alleviate symptoms associated with Meniere's disease.

**Why Each Wrong Option is Incorrect**
**Option A:** Dilating tympanic vessels is not directly related to the pathophysiology of Meniere's disease, which involves the endolymphatic system rather than the tympanic cavity.

**Option B:** Decreasing endolymph secretion would be beneficial in Meniere's disease, but this is not the primary mechanism of action of vasodilators in this context.

**Option D:** This option is a distractor with no relevance to the pathophysiology or treatment of Meniere's disease.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that vasodilators, such as glyceryl trinitrate, are used in Meniere's disease to reduce endolymph pressure by enhancing endolymph reabsorption through the endolymphatic sac.

**✓ Correct Answer: C. Increase endo lymph reabsorption**