<u>A. They are organic molecules that all contain carbon.</u>
Explanation:
All known life on earth is carbon-based. Most molecules used as building blocks are organic i.e. consisting of based on carbon. This means that they consist of atoms of carbon, hydrogen, oxygen with other variations like nitrogen.
Some macromolecules include glucose-based polysaccharides, amino-acid based proteins and lipids consisting of glycerol and fatty acids.
