What are the three parts of the small intestine?

The small intestine consists of three distinct sections: the duodenum, jejunum, and ileum.

The duodenum is the first part of the small intestine, where significant digestion occurs, particularly with the aid of enzymes and bile that break down food. This section is crucial for the initial processing of nutrients.

The jejunum follows, which is primarily responsible for the absorption of carbohydrates and proteins. It has a larger surface area due to its folds, villi, and microvilli, optimizing nutrient uptake.

Lastly, the ileum is the final section of the small intestine, where the absorption of vitamin B12 and bile salts occurs. It connects to the large intestine and plays a key role in completing the digestive process.

This sequence and function highlight why the correct answer pertains specifically to these three segments of the small intestine, distinguishing them clearly from the other options that reference parts of the large intestine or other digestive components.