3. Wind is correct. Wind is always available and will be around as long as Earth is.
4. The correct answer is snowmobiling around a national park. All of the other activities don't produce carbon emission. Solar-powered objects actually help the earth.
5. The answer is the first one. By caulking in windows, you save heat in the winter time or air in the summer. Cloth shopping bags can be reused while plastic is broken down in a landfill.
