Power is produced inexpensively. Air pollution is produced. Oil spills may occur. The local ecosystem may be disrupted.
I gave my students this multiple choice question: What is a disadvantage of using moving water to produce electricity?

Only one answer is correct among these 4 choices:
- Power is produced inexpensively.
- Air pollution is produced.
- Oil spills may occur.
- The local ecosystem may be disrupted.

Could you tell me which one is correct?

The local ecosystem may be disrupted.