I would say because the respiratory system brings in the oxygen for the body and the circulatory system moves it throughout the body with the blood
SO4 -2, or Sulfate
Hope this helps! :)
Answer:
C3H8 +5O2 arrow 3CO2 +4H2O
Ggggggggggggggggggggggggggggggggggggggg
Answer is B. Releases heat and is exothermic