3. Which of the following are NOT types of microorganisms?

a. Prions

b. Viruses

c. Bacteria

d. Earthworms

d. Earthworms

Explanation:

Think about it: have you ever actually seen a prion, virus, or bacterium? No, because they can't be seen with the naked eye. Microorganism means that it's too small (hence the prefix micro-) to see.

Prions are little misfolded proteins. Viruses are nonliving things made up of a protein and nucleic acid. Bacteria are little prokaryotic microorganisms.