Pulmonary circulation is the movement of blood starting from the heart, where deoxygenated, or carbon dioxide-filled, blood leaves from the right ventricle and through the pulmonary valve, then into the left and right pulmonary arteries and arrives at the lungs. During the process of respiration, the carbon dioxide is released and oxygen is added to the blood. Then, the pulmonary veins carry the oxygenated blood back to the heart, entering into the left atrium, completing the circulation. The correct answer is B, pulmonary.