Q: You are presented with the quiz "What can roundworms do?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "roundworms may be free-living or parasitic" and "internal parasites harm their hosts in many ways". So, what's the best answer to the question?

Available options:
* killing insects
* Make money
* survive
* Start fires
* Harm hosts
* Harm themselves
* protect them
* reproduce
The answer is:
Harm hosts