During the Cardiac Cycle, the Aortic and Pulmonic Valves Close

During the cardiac cycle, the aortic and pulmonic valves close after the ventricles contract because the:

A) papillary muscles relax, which allows the valves to close.
B) chordae tendineae contract, which pulls the valves closed.
C) reduced pressure in the ventricles creates a negative pressure, which pulls the valves closed.
D) blood fills the cusps of the valves and causes the edges to merge, closing the valves.