Fact 1: Amphibians have a relatively complex circulatory system with a three-chambered heart.

Fact 2: All frogs are amphibians.

Given the two facts above, answer the question "what have a relatively complex circulatory system with three-chambered heart?" with the following options: 
- sharks
 - humans
 - bacteria
 - Birds
 - blood
 - frogs
 - salmon
 - pacemaker


 

      frogs   