What must you consider when coupling a trailer with ball coupling?

The combination of answers you've selected is correct because both points emphasize essential safety measures when coupling a trailer with a ball coupling, which is outlined in German traffic regulations.

1. The claw of the coupling must close securely: This is crucial for ensuring that the trailer is securely attached to the towing vehicle. If the coupling fails while driving, it could lead to dangerous situations like the trailer detaching and causing accidents.

2. Any support wheel must be lifted and secured before you drive off: This step is important to ensure that the trailer is stable and that the support wheel does not obstruct movement. An unsecured support wheel could cause instability while driving or even damage the trailer.

The third option you did not select, which is that the support wheel must not touch the ground during coupling, is also relevant, as it ensures that the trailer is properly aligned and ready for safe transport. All parts of the correct answer are essential to guarantee a safe operation when towing a trailer. Understanding and following these rules helps prevent accidents and ensures compliance with German traffic law.