Which macromolecule is the main source of energy for living things?

fat

nucleic acid

protein

carbohydrate

The answer is carbohydrates. Carbohydrates are the macromolecules that are used as the main source of energy for all living things. Among the numerous types of organic compounds, there are four major categories found in living things. They are referred to as the macromolecules of life; these are carbohydrates, lipids, protein, and nucleic acids.