Which part of the small intestine is the last and longest portion where most absorption occurs?

• A. Duodenum
• B. Jejunum
• C. Ileum
• D. Cecum

Answer: (C)

The ileum is the last and longest portion of the small intestine, and it provides extensive surface area for continuing absorption after the earlier segments. Its lining is specialized for absorbing what remains in the lumen, and it handles important tasks like reabsorbing bile acids and vitamin B12. Because it’s the final segment and has a long length, it contributes a large absorptive surface to complete the process of nutrient uptake as chyme moves toward the large intestine. The other parts have different primary roles: the duodenum is the first segment where digestion and initial nutrient absorption begin, the jejunum is the main site of most nutrient absorption, and the cecum is part of the large intestine.