Answer:
water
Explanation:
Water puts out fire by creating a barrier between the fuel source and the oxygen source (it also has a cooling effect which has to do with the energy required to convert liquid water into water vapor). It does this because it is a completely, 100% oxidized material. It simply cannot oxidize any further so it will not “burn”. This smothers the fire. The same thing would happen if you used the ashes that remained after a completely spent fire. Or, as I mentioned before, CO2.
