Microorganisms include which of the following?

Microorganisms encompass a diverse group of tiny living organisms that can only be seen under a microscope. The correct answer includes bacteria, viruses, fungi, and protozoa, all of which are classified as microorganisms.

Bacteria are single-celled organisms that reproduce asexually and can be found in various environments. They play vital roles in processes like decomposition and nutrient cycling. Viruses, while not technically considered living organisms outside of a host, are infectious agents that can replicate only within living cells. Fungi, including yeasts and molds, are essential for breaking down complex organic materials and are crucial for ecosystems and human industry. Protozoa are unicellular organisms that often have complex life cycles and can be free-living or parasitic.

This comprehensive inclusion highlights the vast range of life forms categorized as microorganisms, emphasizing their ecological and medical significance. Other options fail to recognize the full diversity of microorganisms by excluding some of these major groups.