Final answer:
Heart, lungs, and muscles become stronger and more efficient in their utilization of oxygen with regular exercise.
Step-by-step explanation:
True. Heart, lungs, and muscles become stronger and more efficient in their utilization of oxygen as they are used more. This is because regular exercise stimulates adaptations in these organs. For example, aerobic exercise, such as running or swimming, increases the size and strength of the heart muscle, allowing it to pump more blood with each beat. As a result, more oxygen is delivered to the body's tissues.