What is the primary function of the right atrium and right ventricle?

The primary function of the right atrium and right ventricle is to pump deoxygenated blood to the lungs. In the circulatory system, the right atrium receives blood that is low in oxygen and high in carbon dioxide from the body through the superior and inferior vena cavae. Once filled, the right atrium contracts and sends the blood into the right ventricle. The right ventricle then contracts, sending this deoxygenated blood through the pulmonary arteries to the lungs.

At the lungs, carbon dioxide is exchanged for oxygen during respiration. This is why the role of the right atrium and right ventricle is critical; they ensure that the blood is sent to the lungs to receive oxygen, which is necessary for the entire body's functioning. Thus, the answer that highlights their role in moving deoxygenated blood to the lungs is the correct one.