The heart has four chambers: left atrium, right atrium, left ventricle and right ventricle. Only the atrium communicates with the ventricle, but not the left and right sides of the heart. The left atrium communicates with pulmonary vein, the right atrium communicates with superior and inferior vena cava, the left ventricle communicates with aorta, and the right ventricle communicates with pulmonary artery. The figure shows the structure of the heart, including right atrium, right ventricle, left ventricle and vascular pulmonary artery connected with the right ventricle.

So choose: C.