Which of the following describes the ability of the respiratory and circulatory system to supply oxygen during prolonged physical activity?

The ability of the respiratory and circulatory systems to supply oxygen during prolonged physical activity is best described by cardio-respiratory endurance. This term refers to the efficiency with which the body can deliver oxygen to working muscles during sustained exercise. High levels of cardio-respiratory endurance allow individuals to engage in longer and more intense physical activities without experiencing undue fatigue.

This endurance is crucial for athletes and physically active individuals as it enhances performance and supports overall health. It is developed through activities that elevate the heart rate and improve oxygen uptake, such as running, swimming, and cycling, which all help in strengthening the heart, lungs, and muscles involved in respiration and circulation.

The other choices do not pertain directly to the ability of the respiratory and circulatory systems in the context of prolonged activity. Contraindicated exercises refer to movements that should be avoided due to potential injury risks. Fixed resistance relates to a type of strength training where the body moves a set resistance through a range of motion. Dynamic training involves exercises that require movement and can improve both strength and flexibility but does not specifically address the endurance of the cardio-respiratory system.