What is a main function of the large intestine?

• A. Absorption of water
• B. Absorption of oxygen
• C. Secretion of insulin
• D. Production of bile

Answer: (A)

The main idea here is what the large intestine does with water and waste. Its primary job is to reclaim water (and electrolytes) from indigestible material, turning what’s left into solid waste. As the material passes through, most of the remaining water is absorbed, which helps regulate hydration and stool consistency. Bacteria in the colon also ferment some fiber, producing short-chain fatty acids that can be absorbed, but the central function is water reabsorption and waste formation. Other options don’t fit because absorbing oxygen isn’t a role of the large intestine, insulin secretion is an activity of the pancreas, and bile production comes from the liver/gallbladder.