Fact 1: Roundworms may be free-living or parasitic. Fact 2: Parasites Shortfin makos host a variety of parasitic copepods. Given the two facts above, roundworms can be free-living or live on a what?

Options are:
A). soil;
B). nest;
C). host;
D). root;
E). stem;
F). habitat;
G). food;
H). commune;
The answer is:
C).