The answer is going to be the letter D, nitrogen. I hope this helps!!
Answer:
I would say the answer would be: 2. The heart contracts and expands to move blood.
Explanation:
The heart is forcing itself to contract and expand so it can move blood throughout the body. If I am wrong, let me know, but I believe that this is correct since it's a function of force.
Answer:
A generation is "all the people who are born and lived at about one time collectively" and is also defined as "the average period in which children are born and grow up, becoming adults and start having children of their own" "currently approximately thirty years"