Final answer:
The jejunum has less mesenteric fat than the ileum because it has a shorter mesentery, making option (a) the correct answer.
Step-by-step explanation:
The statement "Jejunum has less mesenteric fat than does the ileum" is true. The jejunum, which is approximately 0.9 meters (3 feet) in length, has a shorter mesentery compared to the ileum. The ileum, being the longest part of the small intestine at about 1.8 meters (6 feet), has more mesenteric fat because it is designed to contain a larger number of lymphoid follicles, which are distributed throughout the ileum to defend against the multitude of microorganisms present in the distal part of the small intestine. Accordingly, the correct option for the given question is a. True; jejunum has a shorter mesentery.