Roundworms make up the phylum Nematoda, and roundworms Nearly all puppies and kittens have roundworms. Given these facts, what infests nearly all puppies and kittens among the following options:
- insects
 - Nematoda
 - heat or cold
 - water
 - hay fever
 - bacteria
 - parasites
 - the flu


 

  Nematoda       