I believe the answer is Oxygen and Carbon Dioxide. Hope this helps:)
There are many theories about why living thins sleep, however, scientists are still unsure about what the answer to this question may be. Some say it is because of its restorative powers - after a good night's sleep, you feel rested, and all your brain and bodily functions work better than when you are exhausted. During sleep, some rejuvenating and growth hormones are created, which again adds to our advantage. You also relieve stress that has accumulated during the day. These are some of the reasons why we have to sleep.
Answer:
C - Unicellular, prokaryotic, autotrophs or heterotrophs
Explanation:
