What is the main function of the large intestine?

The large intestine plays a crucial role in the digestive system, primarily focusing on the absorption of water and the storage of waste. As food passes through the digestive tract, most nutrients and water are absorbed in the small intestine. By the time the remaining material reaches the large intestine, it is largely composed of indigestible food matter and waste products.

The large intestine's primary function is to absorb any remaining water from this material, which helps to form solid waste (feces). This process is vital for maintaining the body's fluid balance. Moreover, the large intestine also serves as a storage site for this waste before it is expelled from the body. Bacteria in the large intestine also play a part in the fermentation of undigested material, but the main functions are indeed centered around water absorption and waste storage. This is why the choice that highlights these functions best represents the main role of the large intestine.