Answer : The correct option is, A is condensation and B is freezing.
Explanation :
Melting or fusion : It is a type of process in which the phase changes from solid state to liquid state at constant temperature.
Freezing : It is a type of process in which the phase changes from liquid state to solid state at constant temperature.
Evaporation : It is a type of process in which the phase changes from liquid state to gaseous state at constant temperature.
Condensation : It is a type of process in which the phase changes from gaseous state to liquid state at constant temperature.
Sublimation : It is a type of process in which the phase changes from solid state to gaseous state without passing through the liquid state at constant temperature.
Deposition : It is a type of process in which the phase changes from gaseous state to solid state without passing through the liquid state at constant temperature.
The given observations are:
Change A: Gas changes phases to a liquid. → Condensation
Change B: Liquid changes phases to a solid. → Freezing
Hence, the correct option is, A is condensation and B is freezing.