Explanation

Diagram-A As we can see, there is closure of bicuspid and tricuspid valve, it clearly indicates that the blood is coming into the atrium which means they are in the relaxed or diastole position. Diagram-B As in this diagram, bicuspid and tricuspid valves are open and blood goes from the atrium to ventricle, it clearly indicates that there is contraction of atrium. This situation is called atrial systole. Diagram-C In this diagram, the semilunar valves are open means the blood is going to pulmonary artery and aorta respectively. This happens only when there is contraction in the ventricles. This situation is called ventricular systole