Prokaryotic cells: The term "prokaryotic cells" are described as cells that don't consist of "membrane-bound organelles" or "true nucleus". However, the organisms that come under the domain of Archaea and bacteria tend to possess prokaryotic cells and it has been described that organisms that consist of prokaryotic cells are abundant in nature and make most of the Earth Biomass. Prokaryotic cells don't possess the nucleus rather have one chromosome.
In the question above, the correct answer is option D.
Microbes. Bacteria, for example, convert nitrogen and carbon dioxide from the air into usable components that plants and animals can use as essential building blocks. A loss of all microbes would be terrible news for living organisms that can't create or take in these essential nutrients on their own.