Answer: A. Freezing.
Step-by-step explanation: To freeze is to change a substance from liquid to solid by cooling it (like the transformation of water molecules into snow). Condensing is changing a substance from gas to liquid (by cooling it or by raising the pressure), sublimation is the change of a substance from solid to gas by an abrupt drop in the pressure, and finally, evaporation is the process that involves changing a substance from liquid to gas (like when we boil water).