Which class of macromolecules is primarily used as rapidly available energy sources by living thing?

The correct answer is - carbohydrates.

Explanation:

The four significant groups of macromolecules found in living beings are carbohydrates, lipids, nucleic acids, and proteins. carbohydrates comprised of carbon, hydrogen, and oxygen molecules, generally in a proportion of 1 : 2 : 1.

Living things use carbohydrates as their main form of energy.  Carbohydrates are a class of macromolecules is essentially utilized as a quickly accessible energy source by living things.

Thus, the correct answer is - carbohydrates.

not sure if this is what you'r looking for eubacteria and archaebacteria

the answer is cell division : )