**Core Concept**
The median umbilical ligament is a fibrous structure located in the abdominal cavity, which plays a crucial role in the embryological development of the urinary system. It is a remnant of the urachus, a structure that connects the bladder to the allantois during fetal development.

**Why the Correct Answer is Right**
The median umbilical ligament is a fibrous remnant of the urachus, a tube-like structure that connects the bladder to the allantois during fetal development. The allantois is a structure that develops into the urachus, which in turn gives rise to the median umbilical ligament. This ligament is a vestigial remnant of the urachus, which usually obliterates and fibroses after birth.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not relate to the embryological development of the urinary system.
**Option B:** This option is incorrect as it does not accurately describe the origin of the median umbilical ligament.
**Option C:** This option is incorrect as it does not correctly identify the structure that the median umbilical ligament is derived from.

**Clinical Pearl / High-Yield Fact**
The median umbilical ligament is a key landmark in abdominal surgery, particularly during laparoscopic procedures. It is often used as a reference point to identify the location of the bladder and the ureters.

**Correct Answer: C. Urachus. Median umbilical ligament is a fibrous remnant of the urachus.**