Select the statement below that best describes cardiac afterload:
A.It's the volume amount that fills the ventricles at the end of diastole.
B.It's the volume the ventricles must work against to pump blood out of the body.
C.It's the amount of blood the left ventricle pumps per beat.
D.It's the pressure the ventricles must work against to open the semilunar valves so blood can be pumped out of the heart.