Into which chamber of the heart do the superior vena cava, inferior vena cava, and coronary sinus return deoxygenated blood?

The correct answer is the right atrium because it is the chamber of the heart that receives deoxygenated blood returning from the body. The superior vena cava brings blood from the upper part of the body, the inferior vena cava carries blood from the lower part, and the coronary sinus collects blood from the heart muscle itself. All of this deoxygenated blood enters the right atrium, where it is then directed into the right ventricle, which pumps it to the lungs for oxygenation. In contrast, the left atrium and left ventricle deal with oxygenated blood coming from the lungs, and the right ventricle is responsible for pumping deoxygenated blood to the lungs.