are an inexpensive source of energy. cause little pollution to the environment. may hurt the flying animals in the area. are a renewable source of energy.
I gave my students this multiple choice question: Wind is becoming more common as a source of energy. Wind farms require large open spaces for the wind turbines. A negative consequence of this technology is wind turbines

Only one answer is correct among these 4 choices:
- are an inexpensive source of energy.
- cause little pollution to the environment.
- may hurt the flying animals in the area.
- are a renewable source of energy.

Could you tell me which one is correct?

may hurt the flying animals in the area.