Which of the following could replace 'extinguish' as used in the passage?

Directions: Read the following passage carefully and select the most suitable option according to the corresponding number in the passage.

Whenever a fire breaks out (1), the fire brigade throws water on it to cool the burning fuel to a temperature below the ignition point. The soda–acid extinguisher also works on this principle (2).
In the case of fires caused (3) by oil, sprinkling water is not effective. The oil being lighter than water always floats on the surface of the water and continews (4) to burn. In such cases the foam type fire extinguisher, containing acid and sodium bicarbonate solution, is used.
To extinguish (5) fires caused by electricity, water can not be used because this would result in electrocution of the people involved. In such cases, fire extinguisher based on carbon tetrachloride is used. The carbon tetrachloride liquid vaporises on coming in contact with the burning material. Since these (6) vapours are heavier than air, they settle on the burning material and cut off the supply of air. While using carbon tetrachloride extinguisher, it is advisable (7) to cover the mouth and nose with wet cloth to protect oneself (8) from the poisonous effect of carbon tetrachloride vapours.