What position must be selected on the hydraulic selector switch if the truck is to travel and the automatic circuits have failed?

Answer: C — Manual Transfer

When the automatic circuits have failed in a vehicle equipped with a hydraulic system, the hydraulic selector switch must be set to the Manual Transfer position. This selection allows the operator to manually control the vehicle's hydraulic functions, ensuring that essential operations can still be performed despite the automatic features being inoperative. In the Manual Transfer position, the operator has direct control over the hydraulic system, which is crucial in maintaining the vehicle’s mobility and functionality during a failure of the automatic circuits. This manual control typically means that the driver can safely navigate the truck, ensuring that they can react appropriately to the situation. The emergency transfer option would generally be utilized for rapid response situations rather than standard operation, and the automatic transfer setting would not be available if the automatic circuits have failed. The neutral position would not allow for travel at all, as it disengages the drive system. Thus, for safe and effective operation in the event of an automatic failure, selecting the Manual Transfer position is the necessary and correct answer.