When operating a vehicle, what must you observe regarding the vehicle height?

You answered correctly. Each of the selected points is essential when operating a vehicle:

1. Ascertaining the actual height of the vehicle is crucial to ensure compliance with height restrictions on roads, bridges, and tunnels, preventing potential accidents or damage.

2. Knowing the height of any load that extends beyond the vehicle’s external bodywork is vital for safety. This ensures that the overall height does not exceed legal limits and helps avoid collisions with overhead structures.

3. Observing the applicable restraints related to the vehicle's height ensures adherence to regulations, which helps maintain safety on the roads and avoids penalties.

This combination helps to ensure that both the vehicle and its loads are operated safely and legally on German roads, complying with the Straßenverkehrsordnung (StVO), Germany's road traffic regulations.