Fact 1: Chordates have a complete digestive system and a closed circulatory system.

Fact 2: Because reptiles are vertebrates, they are chordates.

Given the two facts above, answer the question "what kind of circulatory system do reptiles have?" with the following options: 
- open
 - systemic
 - complex
 - dense
 - cold
 - three
 - closed
 - organ


 

       closed  