The answer is D. Monsoon.
Frost, dew, fog, and rain are all forms of precipitation, while monsoon is a seasonal wind pattern.
Frost is a thin layer of ice that forms on surfaces when the temperature drops below freezing. Dew is water that condenses on objects overnight when the temperature drops below the dew point. Fog is a cloud that forms at ground level when the air is saturated with water vapor. Rain is water that falls from clouds in the form of drops.
Monsoons are seasonal winds that blow from the land to the sea in the summer and from the sea to the land in the winter. They are caused by differences in temperature between the land and the ocean.