The correct answer is D) Calibrated orifice. In a gas turbine engine, the lube oil supply to each bearing is controlled by a calibrated orifice. The orifice is designed to provide the appropriate amount of lube oil flow to each bearing based on its specific requirements. This ensures that the correct lubrication is delivered to each bearing, preventing damage and ensuring the proper functioning of the gas turbine engine. The other options are incorrect because they do not directly control the lube oil supply to each individual bearing. A regulating valve (A) would control the overall lube oil supply, but not the distribution to each bearing. A flow divider (B) would divide the lube oil flow, but not necessarily in the precise amounts required by each bearing. A lube oil pump (C) would provide the overall lube oil pressure and flow, but the calibrated orifices are responsible for the specific distribution to each bearing.