**Core Concept**
The ovarian fossa is a shallow depression in the pelvic cavity that serves as the site for the ovary. It is bounded by various structures that provide support and protection to the ovary. Understanding the anatomy of the ovarian fossa is crucial for identifying the correct boundaries.

**Why the Correct Answer is Right**
The ovarian fossa is bounded by the ureter, which is a crucial structure for the formation of the fossa. The ureter serves as the medial boundary of the ovarian fossa. The obliterated umbilical artery also forms part of the boundary, serving as the anterior boundary. The internal iliac artery, which is a major branch of the common iliac artery, forms the lateral boundary. However, the internal pudendal artery does not form part of the boundary of the ovarian fossa. Instead, it is a branch of the internal iliac artery that supplies blood to the perineal region.

**Why Each Wrong Option is Incorrect**
**Option A:** The ureter is indeed a boundary of the ovarian fossa, serving as the medial boundary.
**Option C:** The obliterated umbilical artery forms part of the boundary of the ovarian fossa, serving as the anterior boundary.
**Option D:** The internal iliac artery is also a boundary of the ovarian fossa, serving as the lateral boundary.

**Clinical Pearl / High-Yield Fact**
The ovarian fossa is a critical anatomical landmark in gynecology, and identifying its boundaries is essential for performing procedures such as oophorectomy. The obliterated umbilical artery is a key landmark for identifying the location of the ovarian fossa.

**✓ Correct Answer: B. Internal pudendal artery**