The answer is carbon, hydrogen, and oxygen.
Carbohydrates is a type of organic molecule, since all organic molecules contains carbon, hydrogen, and oxygen, carbohydrates are no exception.
Even though different type of carbohydrates contains different ratio and arrangement of the three elements, but their comportment I still the same.
For example in glucose, a simple form of carbohydrate, is composed of 6 carbon, 12 hydrogen, and 6 oxygen atoms.