Among the valves to open when deballasting using tanks 1P and 10P of the DEEP DRILLER is __________.

Correct Answer: Option D — 48 Port

Operating ballast systems on mobile offshore drilling units requires strict adherence to the unit's operations manual and piping diagrams. Valve 48 Port is explicitly lined up in the vessel's ballast control schematic for discharging water specifically from tank 10P during standard deballasting operations.