How is the role of temperature best understood in identifying frost and dew?

Correct answer: Above freezing liquid dew and below freezing icy frost can form

Temperature is the main factor that distinguishes liquid dew from icy frost. When a surface cools below the dew point but remains above the freezing point, water vapour condenses into liquid droplets called dew. If the surface temperature falls to or below freezing, the moisture can form solid ice crystals or freeze, producing frost. The exact result also depends on moisture and surface conditions, but the freezing point provides the basic identification rule used in this question.

Option B is correct because above-freezing conditions can produce liquid dew, whereas below-freezing conditions can produce icy frost. Option A ignores the central role of temperature. Option C reverses the process, since high temperatures do not normally produce frost. Option D is wrong because dew is generally liquid, not always made of ice crystals. Thus, comparing the surface temperature with the freezing point gives the clearest distinction between the two forms of condensation.