Final answer:
The single-celled eukaryotes that are generally motile are known as protozoa, which is answer E). Protozoa are different from bacteria and archaea, as they are eukaryotes with a true nucleus and complex cellular structures.
Step-by-step explanation:
The microbes commonly known as protozoa are single-celled eukaryotes that are generally motile. The correct answer to the question is E) protozoa. Protozoa are unicellular organisms with complex cell structures; most of them have the ability to move. They can achieve motion in several ways, including by means of flagella, cilia, or pseudopodia. Examples of protozoan diseases include malaria caused by the genus Plasmodium and giardiasis caused by the genus Giardia.
Indeed, while bacteria and archaea are classified as prokaryotes because their cells lack a nucleus, eukaryotes such as protozoa have a true nucleus and complex cellular structures. Other groups of microorganisms like fungi (while included in eukaryotic microbes) and helminths (multicellular parasitic worms) are not generally motile in their adult forms. Viruses, though not considered true living organisms or eukaryotes, can also cause diseases.