Fact 1: Roundworms may be free-living or parasitic.

Fact 2: Parasites are organisms that live off a host.

Given the two facts above, answer the question "aside from free-living, where else can roundworms exist?" with the following options: 
- mouth of rivers
 - in the sky
 - loose soil
 - our planet
 - Earth orbiting the Sun
 - live off a host
 - molecules
 - h2o


 

      live off a host   