You are presented with the question "what kind of circulatory system do reptiles have?" and the following answer choices: 
- open
 - systemic
 - complex
 - dense
 - cold
 - three
 - closed
 - organ

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.


 

       closed  