I think it might be d. the lungs expand and contract which increases the rate of blood flow so the muscles can convert and store energy
3 Americans
Hope this helped
The best answer to fill in the blank would be ''Bystander'' because as that role you can go tell any adult or higher authority to stop the fighting so you don't try to be a hero and get yourself hurt as well.
Answer:
Family practitioners and obstetrician-gynecologists, or OB-GYNs
Explanation:
Hold your breath to find your target heart rate, then be calm until ur heart beat slows until it's the slowest, that's ur resting heart rate
