I believe it’s carbon dioxide, because you use your respiratory system to breathe in oxygen, and oxygen goes through your circulatory system. And you breathe out CO2.
Question 3: B. Metabolic Rate
question 4: B. Carbohydrates
question 5: A. Fat Soluble and Water soluble
It can hurt you life style by getting whacked in the face when someone turns it XD
The answer is true ...............................