**Core Concept**
Pilocarpine is a muscarinic receptor agonist used in the management of glaucoma. It works by influencing the dynamics of aqueous humor production and outflow within the eye.

**Why the Correct Answer is Right**
Pilocarpine increases aqueous humor outflow by stimulating the muscarinic receptors on the ciliary epithelium, leading to contraction of the ciliary muscle. This contraction opens the trabecular meshwork, allowing for increased outflow of the aqueous humor. As a result, the intraocular pressure (IOP) decreases. The increased outflow is due to the enhanced uveoscleral pathway, which is the main route of outflow in the presence of pilocarpine.

**Why Each Wrong Option is Incorrect**
**Option A:** Reducing aqueous humor secretion is the mechanism of action of beta-blockers (e.g., timolol), not pilocarpine. Pilocarpine's primary effect is not on reducing the production of aqueous humor.

**Option B:** Contracting the iris sphincter muscle is a response to the parasympathetic stimulation of the iris sphincter muscle, but it is not the primary mechanism by which pilocarpine reduces IOP.

**Option D:** Relaxing the ciliary muscle is actually the opposite of what pilocarpine does. The contraction of the ciliary muscle is necessary for the increased outflow of the aqueous humor.

**Clinical Pearl / High-Yield Fact**
Miotics like pilocarpine are useful in managing acute angle-closure glaucoma, but they can be contraindicated in patients with narrow angles or pseudoexfoliative glaucoma.

**✓ Correct Answer:** C. Increasing aqueous humor outflow