## **Core Concept**
The sigmoid colon receives its blood supply from branches of the inferior mesenteric artery, which is a key component of the gastrointestinal arterial blood supply.

## **Why the Correct Answer is Right**
The inferior mesenteric artery (IMA) arises from the abdominal aorta and supplies blood to the distal part of the transverse colon, descending colon, sigmoid colon, and rectum. Specifically, the sigmoid colon is supplied by the **sigmoid arteries**, which are branches of the inferior mesenteric artery. These sigmoid arteries provide the necessary blood flow to the sigmoid colon.

## **Why Each Wrong Option is Incorrect**
- **Option A:** The superior mesenteric artery primarily supplies the proximal part of the gastrointestinal tract, including the duodenum, jejunum, and ileum, and parts of the large intestine up to the right two-thirds of the transverse colon. It does not supply the sigmoid colon.
- **Option B:** While the middle colic artery, a branch of the superior mesenteric artery, does supply part of the transverse colon, it does not supply the sigmoid colon.
- **Option D:** The internal iliac arteries are primarily involved in supplying blood to the pelvic walls, pelvic organs, external genitalia, and perineum, not the sigmoid colon.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the watershed area between the superior and inferior mesenteric arteries' supply can be a site for ischemia, particularly in low-flow states. The sigmoid colon, being supplied by the inferior mesenteric artery, can be at risk in conditions like acute mesenteric ischemia.

## **Correct Answer:** C. Sigmoid arteries (branches of Inferior Mesenteric Artery).