**Core Concept**
Beta-blockers, a class of medications commonly used to treat hypertension and cardiac arrhythmias, also have a significant role in the management of glaucoma. The primary mechanism of beta-blockers in glaucoma involves the reduction of intraocular pressure (IOP) through the decrease in production of aqueous humor.

**Why the Correct Answer is Right**
The correct answer, **C. Decrease in the production of aqueous humor**, is due to the beta-blockers' ability to inhibit the beta-adrenergic receptors in the ciliary epithelium of the eye. This leads to a decrease in the production of aqueous humor, which in turn reduces the intraocular pressure. This mechanism is particularly beneficial in the treatment of glaucoma, a group of eye conditions characterized by progressive damage to the optic nerve due to increased IOP.

**Option A:** The membrane stabilizing effect of beta-blockers is more relevant to their action in reducing the automaticity of the heart, which is not the primary mechanism in glaucoma.

**Option B:** While beta-blockers may have some neuroprotective effects, this is not their most important action in glaucoma.

**Option D:** Pupillary constriction is not a mechanism associated with beta-blockers in the treatment of glaucoma.

**Clinical Pearl / High-Yield Fact**
Beta-blockers, such as timolol, are often used as the first-line treatment for glaucoma due to their efficacy in reducing intraocular pressure and their well-established safety profile.

**✓ Correct Answer: C. Decrease in the production of aqueous humor**