D, they know not what may happen due to their actions.
The blood (circulatory system) carries oxygen to your lungs (respiratory system). Oxygen binds to the hemoglobin molecule in your blood and is carried back to the heart, then pumped out to the other parts of the body.
Hope this helps :)
It keeps you from working out at too low of an intensity, It helps you adjust your workout, It shows when you are performing cardiovascular exercise, and i<span>t keeps you from working out too hard.</span>
Answer:
I believe your first two are correct but your bottom two should be rearranged. Have you tried looking it up?
Explanation:
I think the correct answer is B.
