What type of sounds are included in the category of avoidable noises according to the German traffic ordinance?

The correct answer is that both honking horns and racing engines are classified as avoidable noises according to the German traffic ordinance. This classification is significant because the ordinance aims to promote road safety and maintain peace in residential areas by limiting excessive and unnecessary noise.

Horns are typically intended for signaling, but using them inappropriately or excessively leads to noise pollution. Racing engines, on the other hand, produce loud sounds which are often seen as a nuisance, particularly in urban settings where quieter environments are desired.

Thus, both types of sounds fall into the category of avoidable noises, as they can be mitigated through responsible vehicle operation and adherence to traffic regulations. The inclusion of both indicates the emphasis on reducing noise pollution from vehicles.