What causes avoidable noise?

The selected combination correctly identifies two actions that contribute to avoidable noise, which is addressed in German traffic regulations. Sounding the horn as a greeting is considered unnecessary and disruptive, as it can disturb others, especially in residential areas. Similarly, slamming doors shut creates excessive noise, which is also avoidable. Both of these actions are discouraged to maintain a peaceful environment and show consideration for others.

Driving with a roof-rack, however, is generally not classified as avoidable noise because it does not inherently produce noise in the same manner as the other two actions. It's important to consider all options in questions like this to ensure a comprehensive understanding of what behaviors are regulated under traffic laws, as they aim to enhance safety and minimize disturbances in shared spaces.