What is true of permanently illuminated signs?

You answered correctly because permanently illuminated signs in Germany indicate which lanes are open or closed to traffic. The red "X" means that those lanes are closed, and vehicles must not use them. The green arrow shows that the lane is open and can be used.

Additionally, these signs prohibit stopping at the side of the carriageway where the signs are illuminated. This rule helps to keep traffic flowing and avoid accidents on busy roads like highways.

The third option is incorrect because the signs apply to all vehicles on the road, not just multi-track motor vehicles. So, understanding these signs helps you know which lanes to use and ensures safety by preventing stopping in unsafe areas.