Atoms of what element form the backbone of large, complex molecules such as sugars and fats?

A. carbon

B. oxygen

C. sodium

D. sulfur

A. Carbon

Carbon is the main constituent element in organic molecules such as fats and sugars. Carbon is the element associated with life as carbohydrates, large molecules made of carbon and hydrogen, are used as sources of energy in the bodies of organisms. Moreover, carbohydrates are stored in the form of fats, which are again composed of a carbon backbone. Even protein molecules have carbon backbones, they differ from other macromolecules due to the presence of nitrogen atoms.