What are the three sections of the small intestine and what role does each section play in digestion or absorption?

The three sections of the small intestine are the duodenum,

Explanation:

The duodenum

It receives chyme from the stomachs

Its intestinal cells enzymes such as secrete amylase, sucrase, and lipase enzymes that break down fats and sugars.

The jejunum

It is covered in villi and microvilli giving the name THE PRINCIPAL SITE of digestion.

the ileum.

Aid absorption e.g. amino acids, lipids, fat-soluble vitamins, and vitamin B12.

The three sections of the small intestine are the duodenum, jejunum and the ileum

Explanation:

Duodenum: The beginning and the shortest part of the small intestine where iron is absorbed. Duodenum is shaped like a letter "C.

Food passes from the stomach to duodenum through a muscle called the pyloric sphincter.

Jejunum: The middle part of the small intestine where sugars, amino acids, and fatty acids are absorbed.

Ileum: The last part of the small intestine where vitamin B12, bile acids, and other nutrients are absorbed

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."