The correct answer to this question is D, energy. Excretion of the lungs helps clean up after respiration. During this processing of respiration glucose and oxygen work together to create carbon dioxide and water. The blood carries them to the lungs , in which they are disposed of during exhalation.
As one exhales, carbon dioxide is released, which is a waste product that appears in the cells. During exhalation, carbon dioxide, along with water is released as gas. This gas exchange in the lungs is called alveoli. By getting rid of carbon dioxide, it helps the lungs continue being in the state of acid base homeostasis.