**Core Concept**
The aqueous humor is a clear fluid produced by the ciliary body, playing a crucial role in maintaining the intraocular pressure and providing nutrients to the avascular cornea and lens. The aqueous humor is secreted by the epithelium of the ciliary body and then flows through the anterior chamber to nourish the cornea and lens.

**Why the Correct Answer is Right**
The aqueous humor secreted by the ciliary body first enters the posterior chamber, which is a small space between the iris and the lens. From there, it flows through the pupil into the anterior chamber, where it is drained by the trabecular meshwork. The posterior chamber receives the newly secreted aqueous humor and allows it to flow towards the anterior chamber.

**Why Each Wrong Option is Incorrect**
* **Option A:** The anterior chamber is the space where the aqueous humor is drained, not where it is first secreted.
* **Option B:** The vitreous body is the gel-like substance filling the posterior segment of the eye, but it is not the space where the aqueous humor is first secreted.
* **Option D:** The suprachoroidal space is a potential space between the choroid and the sclera, but it is not the primary space where the aqueous humor is first secreted.

**Clinical Pearl / High-Yield Fact**
In glaucoma, the trabecular meshwork, which is responsible for draining the aqueous humor, is often clogged, leading to increased intraocular pressure and damage to the optic nerve.

**Correct Answer:** C. posterior chamber.