This lowers the temperature. This makes the flames smaller. This absorbs the burning substance. This keeps oxygen from reaching the fire.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Why can a small fire be put out by placing a heavy blanket over it?
Possibilities:
- This lowers the temperature.
- This makes the flames smaller.
- This absorbs the burning substance.
- This keeps oxygen from reaching the fire.

This keeps oxygen from reaching the fire.