the energy from the ice flows to the sidewalk. the energy from the sidewalk flows to the ice. convection currents flow between the ice and the sidewalk. radiation flows between the ice and the sidewalk.
I gave my students this multiple choice question: A block of ice is placed on a hot sidewalk. The ice melts because

Only one answer is correct among these 4 choices:
- the energy from the ice flows to the sidewalk.
- the energy from the sidewalk flows to the ice.
- convection currents flow between the ice and the sidewalk.
- radiation flows between the ice and the sidewalk.

Could you tell me which one is correct?

the energy from the sidewalk flows to the ice.