What is the primary function of the large intestines (colon)?

The primary function of the large intestines, or colon, is to absorb water. As chyme moves into the large intestine from the small intestine, it contains a significant amount of water and undigested food material. The large intestine's primary role is to reclaim as much water as possible from this material, effectively concentrating the waste into solid feces for elimination. This absorption process is crucial for maintaining the body's fluid balance and ensuring that excessive water loss does not occur.

While the large intestine also performs other functions such as housing gut bacteria that contribute to the fermentation of undigested materials, the absorption of water is its main physiological role. This process is essential for preventing dehydration and maintaining proper physiological function in the body. The other options relate to different functions of the digestive system; nutrient absorption predominantly occurs in the small intestine, bile production happens in the liver, and the digestion of proteins primarily takes place in the stomach and small intestine.