Answer:
The gauge pressure reading stay the same.
Step-by-step explanation:
it is known that altitude is inversely proportional to atmospheric pressure.
the atmospheric pressure decrease as height increases.
gauge pressure is determine by subtracting atmospheric pressure from absolute pressure(the total system pressure).
Pabs = Pg +Patm
gauge pressure is the pressure relative to atmospheric pressure
therefore, since atmospheric pressure kept decreasing at the mountain, the gauge will be the same but the absolute pressure will decrease.
this is so, because it is not stated if the cylinder is open or close, but, I assumed it is closed