Answer:
The correct answer is - oxygen.
Step-by-step explanation:
Cardiovascular endurance is the ability to do physical activity or exercise without affecting or being tired for a longer time period. Aerobic exercise or activity can help to increase cardiovascular endurance.
Improving the cardiovascular system helps in delivering oxygen as per the demands with the help of the heart that pumps the oxygen-rich blood to different organs of an individual and lungs by inhaling enough oxygen.