Biological molecules which contain carbon, oxygen, and hydrogen atoms are defined as carbohydrates.
Carbohydrate is present in both DNA and RNA. Carbohydrates are most abundant bimolecules. Carbohydrates are the most efficient fuel source for the body. Hence, they can be stored in the body.
Hence, the option B, C, and D are wrong.
The most efficient fuel source for the body is carbohydrates. They used to give energy for the bodies.
Hence, the correct option is.