**Core Concept**
The uterus is a pelvic organ with surrounding structures. Identifying its immediate anterior relation is crucial for understanding pelvic anatomy and potential surgical approaches.

**Why the Correct Answer is Right**
The correct answer is **Option C: Bladder**. The bladder is the immediate anterior relation to the uterus in the female pelvis. This is because the uterus is a midline organ and the bladder is a pelvic organ that lies in front of it. The two are separated by the vesicouterine pouch, which is a potential space that can contain fluid.

**Why Each Wrong Option is Incorrect**
* **Option A:** The rectum is the immediate posterior relation to the uterus, not the anterior relation.
* **Option B:** The sigmoid colon may be a lateral relation to the uterus, but it is not the immediate anterior relation.

**Clinical Pearl / High-Yield Fact**
In gynecologic surgery, identifying the correct relations of the uterus is crucial for avoiding injury to surrounding structures. The bladder is a common site for vesicouterine fistulas, which can occur after uterine surgery.

**Correct Answer: C. Bladder**