At the Onset of Ventricular Diastole, the A-V Valves Close

At the onset of ventricular diastole, the A-V valves close as a result of

A) higher pressure in the atria relative to the ventricles.
B) higher pressure in the ventricles relative to the atria.
C) higher pressure in the arteries (pulmonary and aorta) relative to the ventricles.
D) higher pressure in the venae cavae relative to the atria.
E) contraction of the small muscles which attach to the valves.