The correct answer is A. citric acid.
Citric acid is an organic acid found in citrus fruits. It is a weak acid and is used as a food additive, preservative, and flavoring agent. It is also used in the production of other chemicals, such as citrate salts and vitamin C.
Sulphuric acid, nitric acid, and phosphoric acid are all inorganic acids. They are strong acids and are used in a variety of industrial applications, such as the production of fertilizers, detergents, and explosives.
Organic acids are acids that are found in living things. They are typically weak acids and are used in a variety of biological processes, such as the metabolism of food.