Which part of the digestive tract is divided into the duodenum, jejunum, and ileum?

• A. Small intestine
• B. Stomach
• C. Large intestine
• D. Esophagus

Answer: (A)

The small intestine is where most of digestion and nutrient absorption happens, and it is divided into three consecutive sections: the duodenum, jejunum, and ileum. After leaving the stomach, chyme first enters the duodenum, where it mixes with bile and pancreatic juices to start digesting fats and other nutrients. The majority of absorption occurs in the jejunum, which has a highly folded lining to maximize surface area. The ileum completes absorption, including reabsorbing bile acids and vitamin B12. The other options don’t fit because the stomach isn’t organized into those three sections, the esophagus merely transports food to the stomach, and the large intestine focuses on absorbing water and forming stool rather than containing these three regions.