Which of the following is an organic acid?

The distinction of organic acids lies in their carbon-based structure and the presence of carboxylic groups (-COOH). Among the choices provided, acetic acid stands out as an organic compound characterized by a carboxylic acid functional group, making it a straightforward example of an organic acid.

Formic acid, while also an organic acid, may not have been identified as the correct answer here, possibly due to a focus on more commonly recognized organic acids in certain contexts. Hydrochloric acid and sulfuric acid, on the other hand, are inorganic acids. They do not have the carbon backbone characteristic of organic molecules, which solidifies the classification of acetic acid as the representative organic acid in this list.

Understanding this classification helps in differentiating between organic and inorganic acids, which is fundamental in chemistry and various applications in science and industry.