mechanical energy to electrical energy thermal energy to mechanical energy nuclear energy to mechanical energy thermal energy to electrical energy
I gave my students this multiple choice question: After a storm, a hospital may have to rely on backup generators to power some equipment. Which is the energy conversion provided by the generators?

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

Could you tell me which one is correct?

mechanical energy to electrical energy