Deposition is the change of state from which to which; frost forms on a cold surface.

• A. Gas turning directly into a solid; frost forms.
• B. Solid turning into a liquid; melting.
• C. Liquid turning into a gas; evaporation.
• D. Gas turning into a liquid; condensation.

Answer: (A)

Deposition is a phase change where a substance goes from a gas directly to a solid, skipping the liquid stage. Frost forms on a cold surface because water vapor in the air deposits as solid ice, turning straight into ice crystals instead of first becoming liquid.

The other options describe melting (solid to liquid), evaporation (liquid to gas), and condensation (gas to liquid), which are different transitions and do not explain frost formation.