The correct answer is: A. Clear, calm afternoon.
On a clear, calm afternoon, the sun’s rays can reach the ground and heat it up. The warm ground then heats up the air above it. The air near the ground is warmer than the air higher up, so there is a greater temperature difference.
On a cloudy, calm afternoon, the clouds block the sun’s rays, so the ground does not heat up as much. The air near the ground is not as warm as the air higher up, so there is a smaller temperature difference.
On a clear, windy afternoon, the wind mixes the air, so the temperature difference between the ground and the air above it is not as great.
On a cloudy, windy afternoon, the wind mixes the air, but the clouds block the sun’s rays, so the ground does not heat up as much. The air near the ground is not as warm as the air higher up, so there is a smaller temperature difference.