Assertion (A): It is not possible for a system unaided by an external agency to transfer heat from a body at lower temperature to another body at higher temperature.
Reason (R): “According to Clausius statement” No process is possible whose sole result is the transfer of heat from a colder object to a hotter object

Second law of thermodynamics can be explained with the help of example of refrigeration, as we know that in refrigerator, the working substance extracts heat from colder body and rejects a large amount of heat to a hotter body with the help of external agency. No refrigerator can ever work without external supply of electric energy to it.