The correct answer is C) rising and falling with each stroke. When testing a reciprocating refrigeration compressor for leaking discharge valves using the method described, the compound gauge will show pressures that rise and fall with each stroke of the compressor. This is because if the discharge valves are leaking, the compressed refrigerant will be able to flow back into the compressor cylinder on the suction stroke, causing the pressure to rise and fall cyclically. The other options are incorrect because: A) the pressure would not decrease to a vacuum, as there is still refrigerant in the system; B) the pressure would not continuously increase, as it would cycle up and down; and D) the pressure would not continuously decrease, as it would cycle up and down.