washing all clothes in warm water turning off the lights when not in use letting the water run when brushing teeth using bags made of plastic instead of paper
I gave my students this multiple choice question: Which is a good practice to help conserve energy?

Only one answer is correct among these 4 choices:
- washing all clothes in warm water
- turning off the lights when not in use
- letting the water run when brushing teeth
- using bags made of plastic instead of paper

Could you tell me which one is correct?

turning off the lights when not in use