Answer: The lower respiratory system moves oxygen into the blood; the circulatory system delivers blood to the body.
Explanation:
Your answer is B. Do a cost-benefit analysis to compare the alternatives. You have to chose how much you're willing/want to spend, what activities you're willing to spend on/do, and if the benefits of an activity fit or outweigh the costs. Also, not just monetary expenses but costs on your time, relationships, and other aspects of your life should be taken into account as well. Good Luck!
