Why does the blood returning to the heart have very little oxygen in it?

a)the heart is not pumping oxygen fast enough
b)the cells throughout the body used the oxygen.
c)the heart did not receive enough oxygen from the lungs
d)the lungs breathed out too much oxygen

Its totally for health > : ) random questions- free points. 1. grab the book nearest to you, turn to page 18, and find line 4. 2. stretch your left arm out as far as you can, what can you touch? 3. before you started this survey, what were you doing? 4. what is the last thing you watched on tv? 5. without looking, guess what time it is 6. now look at the clock. what is the actual time? 7. with the exception of the computer, what can you hear? 8. when did you last step outside? what were you doing? 9. did you dream last night? 10. do you remember your dreams? 11. when did you last laugh? 12. do you remember why / at what? 13. what is on the walls of the room you are in? 14. seen anything weird lately? 15. what do you think of this quiz? 16. what is the last film you saw? 17. if you could live anywhere in the world, where would you live? 18. if you became a multi-millionaire overnight, what would you buy? 19. tell me something about you that most people don't know. 20. if you could change one thing about the world, regardless of guilt or politics, what would you do?

Where does peer pressure come from? a.the power of culture b.the influences of others c.people who purposely try harm you d.the messages in tv commercials

What is the total amount of waste dissolved in the plasma and what chemical is it