Your friend Ritz eats a lot but still feels weak. As a friend, what advice can you give for Ritz?
A. Eat junk foods to nourish heart and lungs to function properly.
B. Lie in bed all day to allow the heart pumps blood and oxygen to the lungs.
C. Have enough exercise to regulate blood flow in the heart and lungs.
D. Drink more water so that the exchange of gases of heart and lungs will take place.​