The answer is c it is Carbon Dioxide
I looked up what is the molecular formula for Phosphine and got this: PH3
Hope this helps! Let my know if this was correct.
Answer:
I believe CDC I s the most reliable
The circulatory system works with the digestive system. Once the food is digested, the circulatory systems absorb and uses the nutrients in the food. If the digestive system were to break down, the circulatory will not have the nutrients it needs to sufficiently run the body.