Answer:
d. Earthworms
Step-by-step 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.