Final answer:
D) none of the above is the correct answer as the heart, lungs, and muscles are all required to work intensely during a workout.
Step-by-step explanation:
The answer to the question of which is NOT an organ or tissue required to work intensely during a workout is: D) none of the above.
All of the listed options, the heart, lungs, and muscle, are essential and highly active during a workout.
The heart works to pump blood, the lungs oxygenate the blood, and the muscles engage to perform the physical activity.
All tissues require ATP (adenosine triphosphate) to function, and all muscle tissues possess the property of excitability. Oxygen transfer to the tissues is critical during exercise, and factors such as increased body temperature, increased carbon dioxide, and decreased pH can affect this process.
Additionally, the heart is the muscle that performs a tremendous amount of work over a lifetime due to its ability to continuously contract and pump blood without fatigue.