The correct answer is A. Boric acid.
Boric acid is a white, odorless, crystalline solid that is used in a variety of products, including prickly heat powder. It is a mild antiseptic and astringent, and it can help to prevent the growth of bacteria and fungi. Boric acid is also effective at absorbing moisture, which can help to reduce sweating and prevent prickly heat.
Phosphoric acid is a colorless, odorless, syrupy liquid that is used in a variety of products, including soft drinks, fertilizers, and detergents. It is a strong acid that can cause skin irritation and burns.
Carbonic acid is a weak acid that is found in carbonated beverages. It is formed when carbon dioxide gas dissolves in water. Carbonic acid is not used in prickly heat powder.
Sulphuric acid is a strong acid that is used in a variety of products, including batteries, fertilizers, and industrial cleaning products. It is a corrosive acid that can cause skin irritation, burns, and respiratory problems. Sulphuric acid is not used in prickly heat powder.