Which acid is classified as an organic acid?

Acetic acid is classified as an organic acid because it contains carbon atoms in its molecular structure and is derived from living organisms. As a carboxylic acid, its chemical formula is CH3COOH, illustrating the presence of the carboxyl group (-COOH) typical of organic acids. Organic acids are generally characterized by their ability to donate protons (H⁺) in aqueous solutions, a behavior acetic acid exhibits, making it a weak acid compared to the strong mineral acids listed in the other choices.

The other options—sulfuric, hydrochloric, and nitric acids—are classified as inorganic acids. They do not contain carbon in their structures, and they typically come from mineral sources rather than biological processes. This fundamental distinction is what categorizes acetic acid as an organic acid, highlighting the significance of carbon-based compounds in organic chemistry.