**Core Concept**
Descent's membrane stripping in automated penetrating keratoplasty is a surgical procedure used to remove diseased corneal tissue. The endothelial cell layer is a critical component of the cornea, responsible for maintaining corneal clarity by regulating fluid balance.

**Why the Correct Answer is Right**
During Descent's membrane stripping, approximately 50-60% of the endothelial cells are lost due to the mechanical trauma and manipulation of the cornea. This cell loss can lead to long-term complications such as corneal edema and vision loss. The endothelial cell density is an important indicator of the cornea's health, and significant cell loss can compromise the graft's success.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it underestimates the extent of endothelial cell loss. The actual loss is much higher than this value.
**Option B:** This option is incorrect as it overestimates the extent of endothelial cell loss. While some cell loss is inevitable, the actual loss is not as high as this value.
**Option C:** This option is incorrect as it fails to provide a specific percentage of endothelial cell loss. A precise value is necessary to accurately assess the extent of cell loss.

**Clinical Pearl / High-Yield Fact**
It is essential to monitor endothelial cell density post-surgery to prevent long-term complications. A significant drop in cell density can indicate the need for further intervention.

**Correct Answer: C. 50-60%**