Viruses are called:

Correct answer: Parasites. Viruses are obligate parasites: they can multiply only inside living host cells.

Background: Outside a host cell a virus cannot reproduce.

• Predator: A predator hunts and eats other animals.
• Epiphyte: An epiphyte is a plant that grows on another plant without harming it.
• None of these: “None of these” is incorrect because parasites is correct.

Did you know? Antibiotics do not work against viruses; vaccines and antivirals are used instead.

Memory trick: Virus = parasite.