Which of the following is not a function of the small intestine?

The small intestine's function is to break down food and absorb nutrients, not to expel waste. To receive and mix partially digested food from the stomach with digestive juices from the liver and pancreas, the small intestine collaborates with other digestive organs. 

Proteins, carbohydrates, and fats are broken down here into their smallest components by the combination of digestive juices and the physical mixing of food. The main function of the small intestine is to absorb nutrients into the bloodstream via its walls, which are lined with finger-like projections called villi and microvilli that significantly increase its surface area. 

Waste products that are not absorbed by the small intestine pass into the large intestine, where the water and electrolytes absorption occurs and feces are formed.