All three domains include unicellular organisms, archaea, bacteria, and eukarya.
The correct answer is - They supply the energy needed for living processes.
Both the carbon and the nitrogen, are gases that are crucial for the survival of the organisms on the planet. They are mostly used by the producers in the ecosystems, as they need them to manage to perform their cycles, get nutrition, and of course energy. The producers are the basis of the ecosystems, so if they do not have a healthy supply of carbon and nitrogen, the ecosystems on the whole planet will collapse. The carbon and the nitrogen later go from one organism to another as the energy is transferred, and usually end up back into the atmosphere again.
Initially, when scientists were first using the taxonomy system to classify living organisms there were only considered to be 2 kingdoms: plants and animals. However, when the microscope was invented, scientists were able to observe differences in organisms at the cellular level! They were also able to observe microscopic living organisms like bacteria that they had not been able to observe before. Scientists realized it was necessary to add 4 new kingdoms to account for the observations they had not seen before the invention of the microscope.
The person would of died i could be wrong