The correct option is A Left atrium
The left atrium receives 4 pulmonary veins from the lungs through which oxygenated blood enters into the heart.
The right atrium receives superior vena cava, inferior vena cava and coronary sinus through which deoxygenated blood from the upper body parts, lower body parts and heart muscles respectively enter the right atrium.
Left ventricle receives the oxygenated blood from the left atrium.
Right ventricle receives the deoxygenated blood from the right atrium.