What are carbohydrates primarily composed of?

Carbohydrates are primarily composed of carbon, hydrogen, and oxygen atoms. This composition is fundamental to their chemical structure, where the general formula for simple carbohydrates (monosaccharides) can often be represented as Cn(H2O)n, illustrating the ratio of hydrogen to oxygen being 2:1, resembling water.

This unique arrangement allows carbohydrates to serve crucial roles in biological systems, including energy storage and providing structural components in plants and some bacteria. For instance, glucose, a primary energy source for cells, contains six carbon atoms, twelve hydrogen atoms, and six oxygen atoms, fitting the molecular makeup defined for carbohydrates.

Other elements such as nitrogen, sulfur, or phosphorus are not typically found in the chemical structure of carbohydrates, which is why the other options do not accurately represent the composition of these important biomolecules.