The correct option is C Left atrium
Blood enters the right atrium and passes through the right ventricle. The right ventricle pumps the blood to the lungs where it becomes oxygenated. Once oxygenation is complete, the oxygenated blood is brought back to the heart by the pulmonary veins. The pulmonary veins carry oxygenated blood from the lungs into the left atrium from where it is returned for systemic circulation.