The correct answer is option 4, advection fog. Advection fog occurs when a warm, moist air mass moves horizontally over a cooler surface. This could be a snow-covered land surface or a cold current in the sea. As the warm, moist air moves over the cooler surface, it cools down and reaches its dew point, causing water vapor to condense into fog.

Option 1, steam fog, refers to fog that forms when cold air moves over a warmer water surface, causing the water to evaporate and create fog. This is different from advection fog as it involves vertical movement of air.

Option 2, frontal fog, is a type of fog that forms along weather fronts where warm and cold air masses meet. This is not the correct answer as it does not specifically involve the horizontal movement of warm, moist air over a cooler surface.

Option 3, radiation fog, forms at night when the land surface cools down after sunset and the air in contact with the surface cools and reaches its dew point. This is not the correct answer as it does not involve the horizontal movement of air.

Therefore, the correct answer is option 4, advection fog.