Which statement best defines aerobic exercise?

• A. Only activities done without oxygen.
• B. Short bursts with insufficient oxygen supply.
• C. Consistent physical activity where the heart can supply the oxygen that the muscles need.
• D. Any activity that uses only leg muscles.

Answer: (C)

Aerobic exercise means ongoing activity in which the heart and lungs can deliver enough oxygen to the working muscles, allowing energy to be produced with oxygen (aerobic metabolism) for that sustained effort. This is why activities like continuous jogging, cycling, or swimming can be performed for longer periods: the body can supply oxygen to the muscles as they need it.

The other descriptions miss this key point. Working without oxygen describes anaerobic effort, which cannot be sustained for long. Short bursts with insufficient oxygen also point to anaerobic, high-intensity activity. And focusing on using only leg muscles doesn’t define aerobic exercise—it's about how the body gets and uses oxygen during sustained activity.