Fact 1: Awindmill converts wind energy into electricity primarily by using mechanical energy.

Fact 2: Windmills are machines operated by windpower.

Given the two facts above, answer the question "what converts wind energy into electricity" with the following options: 
- clouds
 - mechanical waves
 - windpower operated machines
 - Movement of an air mass
 - solar panels
 - Warm air moving into cold air
 - batteries
 - tectonic plates being pushed together


 

   windpower operated machines      