You are presented with the question "What have a complete digestive system and a closed circulatory system?" and the following answer choices: 
- viruses
 - reptiles
 - phytoplankton
 - mammals
 - bacteria
 - graptolites
 - humans
 - elephants

Now knowing that chordates have a complete digestive system and a closed circulatory system and because reptiles are vertebrates, they are chordates, choose the best answer.


 

  reptiles       