What Is the Primary Function of the AV and Semilunar

What is the primary function of the AV and semilunar valves?

A) to coordinate the autorhythmic movements of the heart
B) to keep the right and left sides of the heart separated
C) to control the speed at which blood enter and leaves the heart
D) to permit blood to flow forward while preventing it from flowing backward
E) The opening and closing of the valves creates the normal patterns of an EKG.