Which type of fog occurs on clear nights with very light breezes and forms when the earth cools rapidly?

Correct Answer: Option B — radiation fog

Radiation fog forms on clear, calm nights when terrestrial radiation cools the earth's surface. This cooling lowers the temperature of the adjacent air layer to its dew point, causing condensation. Light breezes are necessary to mix the cooled air slightly, thickening the fog layer, as described in Bowditch, Chapter 32.