The correct answer is A) continuous running of the compressor. If a refrigeration system is short on refrigerant, the compressor will have to run continuously in an attempt to maintain the desired box temperature. This is because the reduced amount of refrigerant circulating through the system means less heat can be effectively removed, causing the box temperature to rise. The compressor will run continuously to try to compensate for the lack of refrigerant, rather than cycling on and off as it normally would. The other options are incorrect because: B) short cycling indicates a different issue, likely with the water supply; C) high suction pressure would indicate an overcharge of refrigerant, the opposite of a shortage; and D) high discharge pressure could be caused by various factors, not specifically a refrigerant shortage.