What artery supplies blood to the small intestine and portions of the colon?

The artery that supplies blood to the small intestine and portions of the colon is the Superior Mesenteric Artery. This artery branches off from the abdominal aorta and is responsible for vascularizing a significant section of the gastrointestinal tract, including the distal part of the duodenum, the jejunum, the ileum, and the proximal two-thirds of the colon.

The celiac trunk, while critical for supplying blood to the upper abdominal organs, primarily services the liver, stomach, and parts of the pancreas and spleen rather than the small intestine or colon. The internal iliac artery supplies blood to the pelvis and lower limbs, not the gastrointestinal tract. Lastly, the renal artery provides blood to the kidneys, which is unrelated to gastrointestinal supply. Therefore, the Superior Mesenteric Artery is the correct choice as it directly provides the necessary blood flow for the regions mentioned within the question.