You are presented with the quiz "have a circulatory system with one or two hearts" 

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 "clams, oysters and snails are familiar mollusks". 

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


 

    Clams       