Which of the following is used as a food preservative?

Carboxylic acids such as acetic acid (vinegar) and benzoic acid are widely used as food preservatives due to their antimicrobial properties. Aldehydes (e.g., formaldehyde) are toxic and not used in food, ketones (e.g., acetone) are not effective preservatives, and alcohols (e.g., ethanol) are used occasionally but are less common and effective compared to carboxylic acids.