Which statement best describes the difference between atria and ventricles?
A. Atria push blood from the veins to the ventricles, and ventricles push blood from the atria to the arteries.
B. Atria push blood from the ventricles to the arteries, and ventricles push blood from the veins to the atria.
C. Atria are on the bottom of the heart, and ventricles are on the upper part of the heart.
D. Atria receive oxygenated blood, and ventricles receive deoxygenated blood.