Final answer:
The large intestine is the primary organ responsible for absorbing water and some vitamins. It plays a vital role in reabsorbing water from indigestible food, synthesizing vitamins, forming feces, and waste elimination.
Step-by-step explanation:
The organ that functions primarily to absorb water and some vitamins is the large intestine. The large intestine, or colon, is crucial for reabsorbing water from indigestible food material and for processing waste. This organ also synthesizes certain vitamins, forms feces, and eliminates feces from the body. While the ileum, which is part of the small intestine, does absorb nutrients like vitamin B12 and bile salts, it is the large intestine that primarily absorbs the majority of water.
The large intestine consists of the cecum, colon, and rectum. Notably, the colon is divided into four regions: the ascending colon, transverse colon, descending colon, and sigmoid colon. In addition to water reabsorption, the colon's main functions include extracting mineral salts from undigested food and storing waste material. Essential for maintaining fluid balance in the body, the large intestine plays a vital role in the digestive system.