Which statement best describes the primary function of the large intestine?

• A. It primarily absorbs water and electrolytes.
• B. It is the main site of nutrient digestion.
• C. It filters toxins from the blood.
• D. It produces digestive enzymes.

Answer: (A)

The large intestine’s main job is to absorb water and electrolytes and to form solid waste. After most nutrients have been absorbed earlier in the digestive tract, the remaining material moves into the large intestine where water and salts are reabsorbed back into the body. This concentrates the waste and helps create feces. The gut microbiota there can produce small amounts of vitamins, but that’s a secondary benefit, not the primary function. That’s why absorbing water and electrolytes is the best description. The other statements describe roles of other organs or processes: nutrient digestion happens mainly in the small intestine; filtering toxins from the blood is a function of the liver and kidneys; and digestive enzymes are produced by the pancreas and small intestine, not the large intestine.