Which statement is true about the colon’s diameter distribution, if any?

• A. Diameter is uniform throughout
• B. Largest diameter is at the cecum
• C. Largest diameter is at the rectum
• D. Largest diameter is at the ascending colon

Answer: (B)

The main idea is that the colon’s lumen isn’t the same size along its length. It starts widest at the cecum and gradually becomes narrower as you move toward the rectum. The cecum acts as a roomy reservoir receiving contents from the ileum, so its diameter is the greatest among colon segments. As the contents are concentrated and moved along, the lumen size decreases, and the rectum is relatively narrower yet designed for storage and expulsion. So the statement that the largest diameter is at the cecum is true. The other options imply a uniform size or a wider distal segment, which isn’t supported by anatomy.