Which of the following veins is responsible for returning blood from the lower body?

The common iliac vein plays a crucial role in returning blood from the lower body to the heart. This vein is formed by the merging of the internal and external iliac veins, which drain blood from the pelvis and the lower limbs, respectively. It subsequently merges with the other common iliac vein from the opposite side of the body to form the inferior vena cava, the major vein responsible for carrying deoxygenated blood from the lower half of the body back to the heart.

The subclavian vein primarily drains blood from the upper body, particularly from the arms and neck, redirecting it toward the superior vena cava. The great saphenous vein, while significant for draining blood from the superficial tissues of the leg, ultimately drains into the femoral vein, which then contributes to venous return but does not directly drain the lower body in its entirety. The femoral vein is also vital in returning blood from the deep structures of the thigh and leg, and it does play an important role in the overall venous return, but it is not as encompassing in terms of location as the common iliac vein.

Thus, the common iliac vein is accurately identified as the key vessel responsible for collecting and returning venous blood from the lower body