Production of which one of the following is a function of the liver?

The liver’s role in nitrogen metabolism includes converting toxic ammonia (from amino-acid breakdown) into the less toxic compound urea via the urea cycle; urea is then exported for renal excretion [1]. By contrast, hydrochloric acid and mucus are secretions of the stomach’s gastric glands — parietal cells produce HCl and other gastric cells secrete mucus to protect the mucosa — so these are not liver functions [2]. Lipase is primarily produced by the pancreas (and also by some brush-border and gastric enzymes), not the liver. Therefore, production of urea is a canonical hepatic function, making option 2 the correct choice.

Sources

1. [1] https://scienceinsights.org/20-essential-functions-of-the-liver-explained/
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 85