Fact 1: Afire requires oxygen to burn.

Fact 2: If the oxygen is removed, the fire is smothered.

Given the two facts above, answer the question "How do you put out a fire?" with the following options: 
- power
 - boiling
 - protect them
 - electrically
 - smother it
 - evaporation
 - mechanical
 - heating liquids


 

     smother it    