The correct answer is D) remove some refrigerant from the system. When a refrigeration compressor has a high head pressure due to an overcharge of refrigerant, the solution is to remove some of the excess refrigerant from the system. This will lower the high pressure and bring the system back to its normal operating parameters. Raising the high-pressure cut-out (option A) or decreasing the condenser cooling water (option C) would not address the root cause of the high pressure, which is the excess refrigerant. Increasing the condenser cooling water (option B) may help lower the pressure temporarily, but the underlying issue of the refrigerant overcharge would still remain.