Windmills are expensive to build. The wind does not blow all the time. Pollution is not created by windmills. Populations of birds can be reduced by windmills.
I gave my students this multiple choice question: Windmills are used to obtain usable energy from wind. Which would be an advantage of using a windmill?

Only one answer is correct among these 4 choices:
- Windmills are expensive to build.
- The wind does not blow all the time.
- Pollution is not created by windmills.
- Populations of birds can be reduced by windmills.

Could you tell me which one is correct?

Pollution is not created by windmills.