You are presented with the quiz "shellfish have a circulatory system with one or two hearts that pump what" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "mollusks have a circulatory system with one or two hearts that pump blood" and "an abalone is a shellfish or mollusk". 

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


 

      blood     