Mollusks have a circulatory system with one or two hearts that pump blood, and clams, oysters and snails are familiar mollusks. Given these facts, have a circulatory system with one or two hearts among the following options:
- Birds
 - alpacas
 - elms
 - Clams
 - salmon
 - animals
 - toads
 - complex


 

    Clams     