The correct answer is D) Open the pump suction valve prior to admitting steam to the turbine. This is the correct answer because it is important to ensure that the pump suction valve is open before applying steam to the turbine-driven feed pump. This allows the pump to draw in the necessary water supply and prevents damage to the pump from running dry. The other options, while potentially relevant in other situations, do not directly address the critical step of opening the suction valve before starting the turbine. Options A, B, and C may be important considerations for the overall start-up procedure, but they do not specifically address the key step of ensuring the suction valve is open to supply water to the pump before admitting steam to the turbine.