Which Statement Best Differentiates Cardiac Afterload from Cardiac Preload

Which statement best differentiates cardiac afterload from cardiac preload?

A) Cardiac afterload is the volume of blood in the heart at the end of diastole.
B) Cardiac afterload is the amount of resistance that the ventricle must overcome.
C) Cardiac afterload is the factor that affects cardiac output.
D) Cardiac afterload is the amount of blood that enters the right atrium.