During the cardiac cycle,

A) the right atrium and the right ventricle contract simultaneously.
B) the two atria relax while the two ventricles contract.
C) the left atrium contracts before the right atrium.
D) all four chambers of the heart contract at the same time.
E) all four chambers of the heart are in systole at the same time.

Cardiac Cycle

The sequence of events that occur in a complete heartbeat, including contraction and relaxation of the atria and ventricles.

Right Atrium

The right upper chamber of the heart that receives deoxygenated blood from the body and pumps it to the right ventricle.

Systole

Contraction of the heart chambers during which blood leaves the chambers; usually refers to ventricular contraction.