You are presented with the quiz "What group of animals do frogs belong to?" 

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 have a three-chambered heart, consisting of two atria and a single ventricle". 

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


 

      Amphibians     