Your answer would be $4 times $y.
Hope this helps; have a great day!
When you breath oxygen enters your body and gets transported to your blood cells
Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide in the process of respiration, which is then used in photosynthesis. While water is broken down to form oxygen in photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water. ATP is manufactured as a result of several processes including fermentation, respiration and photosynthesis.
I think the correct answer from the choices listed above is option B. You can find methanogens in the human intestines. These organisms can work with or without oxygen. Too much of oxygen for them is toxic. They are obligate anaerobes.