How do the ventricles contribute to blood circulation?

The ventricles play a crucial role in the circulatory system, and their primary function is to contract and push blood out of the heart. During the cardiac cycle, when the ventricles contract (a phase known as systole), they generate the pressure necessary to propel blood into the pulmonary artery (from the right ventricle to the lungs for oxygenation) and into the aorta (from the left ventricle to the rest of the body). This contraction effectively ensures that oxygen-depleted blood is sent to the lungs for reoxygenation, while oxygen-rich blood is delivered to various tissues and organs throughout the body.

Other options present different aspects of the cardiac cycle but do not strictly capture the primary role of the ventricles in blood circulation. While filling with oxygen-rich blood and relaxing to allow blood flow are important processes, they represent the phases of diastole and are not the direct actions of the ventricles contributing to blood circulation. Similarly, receiving blood from the aorta describes the role of the systemic circulation and does not reflect the fundamental function of the ventricles. Thus, contraction and pumping action is the defining feature of the ventricles' contribution to circulation.