**Core Concept:** Descemet's membrane is a thin layer of extracellular matrix that lines the inner surface of the cornea. It plays a crucial role in maintaining corneal integrity, transparency, and wound healing.

**Why the Correct Answer is Right:** Descemet's membrane is a continuous layer that extends from the corneal endothelium to the corneal stroma, ensuring proper corneal function and structure. In this case, the correct answer refers to the termination of Descemet's membrane, which is at the junction between the endothelial layer and the corneal stroma.

**Why Each Wrong Option is Incorrect:**

A. This option is incorrect because Descemet's membrane does not terminate at the limbus, marking the junction between the cornea and the conjunctiva.
B. This option is incorrect as Descemet's membrane extends from the endothelial layer to the corneal stroma, not to the sclera.
C. This option is incorrect as Descemet's membrane terminates at the junction between the endothelial layer and the corneal stroma, not in the iris.
D. This option is incorrect because Descemet's membrane terminates at the junction between the endothelial layer and the corneal stroma, not in the aqueous humor.

**Clinical Pearl:** Understanding the anatomy and function of Descemet's membrane is essential for diagnosing and treating various corneal diseases, such as bullous keratopathy and Fuchs dystrophy. A proper knowledge of its termination site helps in correlating the clinical findings with the underlying pathophysiology.

**Correct Answer:** D. Descemet's membrane terminates at the junction between the endothelial layer and the corneal stroma. This ensures the proper functioning of the cornea, including maintaining transparency and facilitating wound healing. Understanding this anatomy is crucial for understanding and managing corneal diseases affecting the corneal endothelium and stroma.