You are presented with the question "What do windmills use to convert energy?" and the following answer choices: 
- Heat
 - fibers
 - copper
 - cycles
 - SO2
 - Vanes
 - calcite
 - Lift

Now knowing that awindmill converts wind energy into electricity primarily by using mechanical energy and windmills tap into the energy of the wind using sails or vanes, choose the best answer.


 

      Vanes   