what have a relatively complex circulatory system with three-chambered heart?
sharks humans bacteria Birds blood frogs salmon pacemaker
A B C D E F G H
All frogs are amphibians.
frogs have a relatively complex circulatory system with a three-chambered heart
what have a relatively complex circulatory system with three-chambered heart? (A) sharks (B) humans (C) bacteria (D) Birds (E) blood (F) frogs (G) salmon (H) pacemaker