You want to couple on a multiple-axle trailer. What must you ensure?

When coupling a multiple-axle trailer, it's crucial to follow specific safety rules to prevent accidents or injuries.

1. Securing the trailer against rolling away is important because if the trailer is not properly secured, it could roll down an incline or cause an uncontrolled situation, putting people and property at risk. This aligns with regulations regarding the responsibility of drivers to ensure that their vehicles are stable and safe to operate.

2. Ensuring that no one remains between the motor vehicle and the trailer during the coupling process is also vital. This is to protect individuals from the possibility of being injured if the vehicle moves unexpectedly or if the trailer becomes detached. It emphasizes the importance of safety protocols during coupling to prevent accidents.

The missed option, which pertains to connecting the brake lines just before docking, is important because proper function of the trailer's braking system is essential for safe operation. However, this step is not the primary concern during the actual coupling process since the trailer must still be secured and clear of personnel.

Understanding and following these combinations of rules is essential for safe operation in accordance with German traffic laws, which emphasize the importance of safety in all vehicular operations.