Final answer:
The large intestine primarily absorbs water and electrolytes, after the small intestine has absorbed most nutrients.
Step-by-step explanation:
The primary substances absorbed in the large intestine are water and electrolytes. While the small intestine is mainly responsible for absorbing nutrients such as lipids, carbohydrates, proteins, and most vitamins, the large intestine concentrates on absorbing the leftover water and electrolytes after the small intestine has completed its part of the digestive process. The large intestine also forms feces from the indigestible residue, which includes undigested plant fibers such as cellulose.