Which of the following is NOT one of the liver's main functions?

The liver is essential for numerous functions within the body, and a foundational aspect of its role is metabolism, including the processing of nutrients from digestion, the production of proteins, and the regulation of glucose levels. Detoxification is another critical function, as the liver helps filter toxins from the blood, breaking down harmful substances to eliminate them from the body. Digestion relates closely to the liver's production of bile, which is crucial for the digestion and absorption of fats.

Regeneration, while an important characteristic of the liver (having the ability to regenerate itself after injury or surgical removal), is not categorized as one of its main functions in terms of physiological processes it performs for the body. Functions refer to the active roles the liver plays in metabolism, digestion, and detoxification, rather than its capacity to heal or regenerate. Therefore, regeneration is the correct answer as it does not align with the functional categories of metabolism, digestion, and detoxification.