conventional diesel fuel distilled kerosene conventionally produced vegetable oil organically produced vegetable oil
I gave my students this multiple choice question: Diesel engines can burn many kinds of fuel. Which fuel would be the most renewable fuel for a diesel engine?

Only one answer is correct among these 4 choices:
- conventional diesel fuel
- distilled kerosene
- conventionally produced vegetable oil
- organically produced vegetable oil

Could you tell me which one is correct?

organically produced vegetable oil