Which statement accurately describes the function of the heart and lungs and the effect of regular exercise?

Which statement accurately describes the function of the heart and lungs and the effect of regular exercise?

• A. The heart pumps blood; the lungs exchange gases; regular exercise strengthens both heart and lungs.
• B. The heart pumps blood; the lungs exchange gases; exercise has no significant effect on these systems.
• C. The heart carries nutrients to cells; the lungs process digestion; exercise improves mood.
• D. The heart pumps blood; the lungs supply oxygen; regular exercise strengthens both heart and lungs.

Answer: (D)