**Core Concept**
The canal of Schlemm is a circular, ring-like structure located at the junction of the iris and ciliary body in the eye. It plays a crucial role in aqueous humor drainage by collecting it from the anterior chamber and transporting it to the bloodstream through the trabecular meshwork.

**Why the Correct Answer is Right**
The canal of Schlemm is characterized by a circular, ring-like shape, which is essential for its function. It is formed by a single layer of endothelial cells that line the canal, allowing for the smooth passage of aqueous humor. The trabecular meshwork, a spongy tissue located within the canal, facilitates the filtration of aqueous humor into the bloodstream.

**Why Each Wrong Option is Incorrect**
* **Option A:** The canal of Schlemm is actually not a simple tube, but rather a circular, ring-like structure with a series of trabecular beams that converge to form a central opening. This incorrect option oversimplifies the canal's anatomy.
* **Option B:** The canal of Schlemm is indeed located at the junction of the iris and ciliary body, but it is not a blind-ending tube. This option mischaracterizes the canal's connection to the anterior chamber.
* **Option D:** The canal of Schlemm is not a structure that is located within the cornea. This option incorrectly localizes the canal within the eye.

**Clinical Pearl / High-Yield Fact**
The canal of Schlemm's function is crucial for maintaining normal intraocular pressure. Damage to this structure can lead to glaucoma, a condition characterized by increased intraocular pressure that can cause vision loss if left untreated.

**Correct Answer: None of the above**