The correct answer is B) at the end of the supply line header to the bearings. The low turbine oil pressure alarm sensor is typically installed at the end of the supply line header to the bearings because this is the location where the oil pressure is lowest in the system. By placing the sensor here, it can detect a drop in pressure that could indicate a problem with the oil supply, before the oil reaches the critical main bearings. The other options are incorrect because they are not the optimal location for detecting a low oil pressure condition. Placing the sensor on the outlet side (A) or at the thrust bearing (C) would not provide an early warning, and the inlet side (D) would not indicate a problem with the oil supply.