Why is a healthy diet important?

• A. It maintains a constant body temperature.
• B. It prevents damage to internal organs.
• C. It makes oxygen for all the cells in the body.
• D. It supplies the body's needs for growth and energy.

Answer: (D)

A healthy diet matters most because it supplies the body's needs for growth and energy. The foods you eat provide the energy you use to walk, study, and breathe, and they also give the building blocks your body uses to grow, repair tissues, and make essential substances like enzymes and hormones. Carbohydrates and fats fuel daily activity, while proteins supply amino acids for growth and tissue repair. Vitamins and minerals support metabolism, bone health, immunity, and many other processes, helping you stay healthy as you grow.

The other ideas aren’t the main reason a healthy diet is important: keeping an exact body temperature is handled by the body’s cooling and warming systems, not by food alone; oxygen is produced by the lungs and carried by the blood, not made by eating; and while a good diet can reduce risk to organs, it doesn’t directly “prevent damage” in every case—the core benefit is providing energy and nutrients for growth and daily functioning.