Mollusks have a circulatory system with one or two hearts that pump blood, and clams are mollusks that live in the sea or in freshwater. Given these facts, what have a circulatory system with one or two hearts that pump blood among the following options:
- a fish
 - aorta
 - bacteria
 - animals
 - clams
 - plants
 - sharks
 - Birds


 

     clams    