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.
Windmills are used to obtain usable energy from wind. Which would be an advantage of using a windmill?

Options:
- 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.

Pollution is not created by windmills.