The correct answer is C) the pump discharge. According to the regulations governing fire protection systems on tankships, each fire pump must have a pressure gauge located at the pump discharge. This allows the operator to monitor the pressure being produced by the fire pump, which is crucial for ensuring adequate water pressure and flow to the fire stations throughout the vessel. The other answer choices are incorrect because they do not specify the location required by the regulations. Fire station discharges (A) and the pump station (D) are not the locations where the pressure gauge must be installed. The manifold connection (B) is also not the correct location, as the pressure gauge must be at the pump discharge specifically.