**Core Concept**
The hypogastric sheath is a fascial layer that encloses the internal iliac artery and its branches. The ligamentous extensions of the hypogastric sheath include several structures that provide support and anchorage to the pelvic viscera. These structures are critical for understanding pelvic anatomy and surgery.

**Why the Correct Answer is Right**
The ligamentous extensions of the hypogastric sheath include the **iliolumbar ligament**, **lateral ligament of the rectum**, and **middle rectal artery ligament**. These structures provide a fascial framework that supports the pelvic viscera and helps maintain pelvic stability.

**Why Each Wrong Option is Incorrect**
**Option A:** **Option A** is not a ligamentous extension of the hypogastric sheath.
**Option B:** **Option B** is not a ligamentous extension of the hypogastric sheath.
**Option D:** **Option D** is not a ligamentous extension of the hypogastric sheath.

**Clinical Pearl / High-Yield Fact**
The hypogastric sheath and its ligamentous extensions are critical for understanding pelvic anatomy and surgery. These structures provide a fascial framework that supports the pelvic viscera and helps maintain pelvic stability.

**Correct Answer: C. None of the above**