Final answer:
The jejunum and ileum are supplied with blood by the superior A) mesenteric arteries, a branch of the abdominal aorta.
Step-by-step explanation:
The jejunum and ileum receive their blood supply from the superior mesenteric artery, which is a branch of the abdominal aorta. This artery arises approximately 2.5 cm after the celiac trunk and has several major branches that supply blood to the small intestine components (the duodenum, jejunum, and ileum), as well as the pancreas, and most of the large intestine. Thus, the correct answer to which arteries supply blood to the jejunum and ileum is A) Mesenteric arteries.