The correct answer is: D. All of the above
Frost forms when objects on the ground cool below the dew point temperature. The dew point is the temperature at which the air is saturated with water vapor. When the air cools below the dew point, the water vapor condenses onto objects on the ground, forming frost.
Frost can also form when water vapor changes into ice without first becoming a liquid. This process is called deposition. Deposition occurs when the air is very cold and the water vapor molecules have very little energy. The water vapor molecules simply attach to the objects on the ground and form ice crystals.
Frost can be a beautiful sight, but it can also be a nuisance. Frost can damage plants and crops, and it can make roads and sidewalks slippery.