Conversation so far:
What are the different types of macromolecules?
Proteins.Carbohydrates.Lipids.Nucleic Acids.
Tell me about the characteristics of carbohydrates.
Its basic structure is composed of the elements carbon, hydrogen and oxygen, with generally twice the hydrogen as carbon and oxygen. In its simplest form, a carbohydrate is a chain of sugar molecules called monosaccharides.

Question: What are they composed of?
Self-contained rewrite: What are carbohydrates composed of?