401 Short cycling of the potable water pump is avoided by the proper use of a __________.

A.hydro-pneumatic tank completely filled with compressed air at system operating pressure
B. hydro-pneumatic tank filled with water
C. charge of air, at 20 psi (137.9 kPa) above system pressure with the hydro-pneumatic tank one quarter full of water
D. charge of air, at system pressure, when the hydro-pneumatic tank is half full of water