What is correct when coupling a full trailer?

The correct options for coupling a full trailer are crucial for ensuring safety during the process.

1. The requirement that the position should be in the driver's line of vision and guide him ensures that the driver has a clear view of the coupling process. This is vital to avoid accidents and ensure correct alignment when connecting the trailer.

2. The warning about obstacles and road users that are not visible to the driver is essential as it emphasizes the need for caution. This helps prevent incidents where the driver may not see other vehicles or pedestrians, especially when maneuvering.

Option 3, which you did not select, is also important as it addresses the physical action of holding the drawbar until it locks into the hitch. This is crucial for ensuring that the trailer is securely attached before setting off.

Overall, selecting all relevant options is necessary because each part ensures an aspect of safety and adherence to the laws governing vehicle towing, helping to prevent accidents and ensuring safe driving conditions on the road.