tidal pull of the moon's gravity evaporation of water from soil in the valley warming by solar energy re-radiated from the ground cooling effect of ice crystals in the air over the mountain
I gave my students this multiple choice question: An air mass in a valley travels up a mountainside. What causes the movement of this air?

Only one answer is correct among these 4 choices:
- tidal pull of the moon's gravity
- evaporation of water from soil in the valley
- warming by solar energy re-radiated from the ground
- cooling effect of ice crystals in the air over the mountain

Could you tell me which one is correct?

warming by solar energy re-radiated from the ground