The Heart Is Called a Double Pump Because _

The heart is called a double pump because _ .

A) blood flows into the receiving chambers, which pump it to the muscular chambers that pump it again for distribution
B) every chamber has a strong pumping action
C) it is two separate side-by-side pumps serving different circulations
D) blood is sent from one pump that imparts a small pressure directly into a second pump that imparts higher pressure