Fact 1: Astove is used for cooking by generating heat.

Fact 2: Warmth generated by staff and machinery heats the air, causing it to rise.

Given the two facts above, answer the question "A stove is used for cooking by heating the what?" with the following options: 
- air
 - weather
 - coal
 - pan
 - gas
 - bed
 - pets
 - fire


 

 air        