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
A:
windpower operated machines