True or False: Blood enters the right ventricle after contraction of the right atrium.

The statement is true because blood enters the right ventricle following the contraction of the right atrium during the cardiac cycle. This process begins when the right atrium fills with deoxygenated blood returning from the body through the superior and inferior vena cavae. When the right atrium contracts, it pushes blood through the tricuspid valve into the right ventricle. This is a normal part of the heart's functioning, setting the stage for the right ventricle to subsequently contract and pump blood into the pulmonary artery, where it becomes oxygenated in the lungs. This cycle is crucial for maintaining proper blood circulation in the body.

Other choices present scenarios that do not accurately reflect how the heart operates during the cardiac cycle or use terms that do not correspond with standard physiological processes. For example, blood does not enter the right ventricle exclusively during exercise; this is a continuous part of the heart's functioning regardless of the level of physical activity.