The answer is B. The respiratory system and circulatory system.
During cellular respiration, cells use oxygen to oxidize glucose. Oxidation of glucose releases energy and carbon dioxide. Carbon dioxide is a waste product. It must be removed from cells. With help of circulatory system, carbon dioxide is transported through the blood from the cells to the lungs. Lungs are the part of respiratory system, from there carbon dioxide is expelled out via trachea and nostrils.
