Final answer:
The ileum is the longest part of the small intestine and connects to the cecum at the ileocecal sphincter. The ileum is also the correct answer to the student's question regarding a part of the small intestine.
Step-by-step explanation:
The part of the small intestine that is directly connected at its distal end to the large intestine is the ileum. The ileum is approximately 1.8 meters (6 feet) in length, making it the longest part of the small intestine. It is responsible for absorbing vitamin B12, bile salts, and any remaining nutrients not absorbed in the jejunum.
The ileum joins the cecum, which is the first portion of the large intestine, at the ileocecal sphincter. Answering the student's initial question, the ileum (A. Ileum) is a part of the small intestine. As for the reference question provided, the part of the large intestine that attaches to the appendix is the cecum (option a.).