Blood is returned from the kidneys to the heart by way of the:

Blood from the kidneys returns to the heart via the inferior vena cava. The inferior vena cava is a large vein that collects deoxygenated blood from the lower parts of the body, including the abdomen and legs, as well as from the kidneys. The renal veins, which drain blood from the kidneys, empty directly into the inferior vena cava. This pathway is crucial for ensuring that the blood filtered by the kidneys is sent back to the heart for re-oxygenation in the lungs and subsequent circulation throughout the body.

In contrast, the renal arteries are involved in delivering blood to the kidneys rather than returning it. The splenic arteries supply blood to the spleen and are unrelated to the renal blood flow. The coronary sinus is responsible for collecting deoxygenated blood from the heart muscle itself and directing it back to the right atrium, but it does not play a role in blood return from the kidneys. Therefore, the function and pathway of the inferior vena cava make it the correct choice for this question.