constructing a small hydroelectric plant placing solar panels on the roof of the house using gasoline generators burning coal or wood
I gave my students this multiple choice question: A house is built in a desert, where there is no electricity and very little wind. Which action could lead to operating the electrical appliances in the house that would cause the least amount of environmental pollution?

Only one answer is correct among these 4 choices:
- constructing a small hydroelectric plant
- placing solar panels on the roof of the house
- using gasoline generators
- burning coal or wood

Could you tell me which one is correct?

placing solar panels on the roof of the house