Final answer:
A rise in the return air wet bulb temperature typically causes reduced cooling capacity in an air conditioner as the system has to work harder to cool and dehumidify the air, resulting in an increased compressor load.
Step-by-step explanation:
When the return air wet bulb temperature rises in an air conditioning system, it typically denotes an increase in humidity and temperature of the air that the system is taking in. This can lead to reduced cooling capacity, as the air conditioner must work harder to cool and dehumidify the air. Consequently, this means that the compressor load would increase, not decrease, due to the higher amount of moisture in the air that needs to be condensed out. Therefore, the correct answer to the question is c) Reduced cooling capacity.
The quality of air conditioners and refrigerators is assessed based on the concept of the coefficient of performance (COP), which is the ratio of the amount of heat transfer Qc that occurs from a cold environment to the work input W that is required. An increase in return air wet bulb temperature would typically lead to a decrease in COP because the system has to do more work to achieve the same amount of cooling, implying reduced efficiency.