Cardiac veins drain blood into the, which will empty into the. a. coronary sinus; left atrium.
b. great cardiac vein; superior vena cava.
c. great cardiac vein; left atrium.
d. inferior vena cava; right atrium.
e. coronary sinus; right atrium.

Option E.

Coronary sinus, right atrium.

Explanation:

Coronary sinus, right atrium is part of the circulatory system that consist of arteries, arterioles, veins, capillaries that move blood to the heart tissue and remove waste from the blood.

The cardiac veins return deoxygenated blood to the right atrium and it them moves to the right ventricle then to the heart where it becomes oxygenated

The coronary sinus received drain blood from ventricles veins, it then moves the deoxygenated blood to the right atrium which it transfer or move to the right ventricle (through the tricuspid valve which in turn move the blood to the pulmonary artery for pulmonary veins.