You are presented with the question "What group of animals do frogs belong to?" and the following answer choices: 
- four limbs
 - animals
 - fish
 - warm-blooded
 - reptiles
 - Amphibians
 - more abundant
 - mammals

Now knowing 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, choose the best answer.


 

      Amphibians   