You are presented with the quiz "What sort of circulatory system do frogs, toads, and salamanders share?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "amphibians have a relatively complex circulatory system with a three-chambered heart" and "frogs, toads and salamanders are amphibians". 

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


 

       three-chambered heart    