You are presented with the quiz "organisms belonging to the phylum Platyhelminthes have evolved a close association with their what" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "flatworms belong to the phylum Platyhelminthes" and "parasitic flatworms have evolved a close association with their hosts". 

So, what's the best answer to the question?


 

      hosts     