Why is frost seen more often on winter mornings?

Correct answer: Because the surface can cool below freezing at night

Answer: B. Frost is most likely when a surface cools to 0°C or below and available water vapour changes into ice crystals. Winter nights are often long and cold, so exposed ground, grass, roofs, and leaves can lose enough heat to fall below the freezing point. By morning, the deposited ice crystals are visible as frost. A is wrong because high temperature prevents freezing. C is wrong because winter air can still contain water vapour; frost needs moisture, not its complete absence. D is wrong because summer temperatures are generally too high for widespread frost, although unusual local conditions can differ. Memory cue: dew forms above freezing; frost forms when the cooled surface is at or below freezing.