Final answer:
Protozoa are the correct answer as they are single-celled eukaryotes and often motile, which fits the description in the student's question. The correct option is E) protozoa
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. Eukaryotic microbes such as protozoa have complex cell structures and are capable of movement, using mechanisms like flagella, cilia, or pseudopodia.
Unlike bacteria and archaea, which are prokaryotes, protozoa have a defined nucleus within their cell structure. Archaea are known to inhabit various environments, but they do not fit the description in the question because they are not eukaryotic.
Viruses are not considered cellular organisms at all, fungi are mostly multicellular, and not all are motile, and bacteria are prokaryotes, so they also do not meet the criteria described in the question. The correct option is E) protozoa