electrical to thermal thermal to mechanical chemical to mechanical mechanical to electrical
I gave my students this multiple choice question: Falling and rising air and water molecules inside of clouds are believed to be factors in the formation of lightning. Which kind of energy transfer is taking place to cause this weather phenomenon?

Only one answer is correct among these 4 choices:
- electrical to thermal
- thermal to mechanical
- chemical to mechanical
- mechanical to electrical

Could you tell me which one is correct?

mechanical to electrical