Answer:
I think the answer is <em>D or A</em>
Explanation:
One is blood bro, “blood flo”
Those two are the muscular system and the excretory system because you use your muscles to push up and down and your excretory system produces the sweat you use while doing them
All of the above apply to your question
B is your answer, it can indicate when you are working above, below, or in your target zone.
