Final answer:
Most nutrients are absorbed in the small intestine, particularly in the jejunum, where carbohydrates and amino acids are absorbed. The villi in the jejunum increase the surface area for absorption.
Step-by-step explanation:
The majority of nutrients are absorbed in the small intestine, specifically in the jejunum. The jejunum is the second part of the small intestine where most of the absorption of carbohydrates and amino acids occurs. The inner surface of the jejunum is covered with structures called villi, which increase the surface area for absorption. The ileum, the last part of the small intestine, also plays a role in absorbing some remaining nutrients.