A two-axle trailer with overrun brakes and fifth-wheel steering is parked on a slope. How must it be secured against rolling?

Your answer is correct because when parking a two-axle trailer with overrun brakes and fifth-wheel steering on a slope, the trailer must be secured to prevent it from rolling. According to German traffic rules, this is done primarily by engaging the parking brake (option 1) and using wheel chocks under the rear wheels (option 2). The parking brake helps hold the trailer in place mechanically, while wheel chocks provide additional security by physically blocking the wheels. Supporting the forked draw-bar (option 3) does not prevent rolling and is not considered a proper measure for securing the trailer on a slope. Together, using the brake and wheel chocks ensures safety and compliance with regulations.