Question

aerobic fitness is how well the body transports and utilizes
oxygen
hydrogen
food
carbon dioxide

Explanation:

Aerobic fitness relates to the body's ability to use oxygen during sustained physical activity. Aerobic processes in the body (like in cellular respiration) rely on oxygen transport and utilization. Hydrogen, food, and carbon dioxide don't fit the core definition of aerobic fitness's focus on oxygen.

Answer:

A. oxygen