What type of trailers used in agriculture and forestry do not have to have their own registration number?

In Germany, certain trailers used in agriculture and forestry are exempt from having their own registration number under specific conditions. The correct combination of choices indicates that trailers which have a "25" speed limit sign attached to the rear and are used to transport agricultural goods do not need individual registration, as long as they do not exceed the 25 km/h speed limit.

Trailers that may travel in excess of 25 km/h will require their registration number regardless of their use. This regulation ensures that slower agricultural vehicles can operate safely on roads without needing the same level of registration as faster, roadworthy trailers, thus facilitating agricultural operations while maintaining road safety. Therefore, it is crucial to consider all aspects of the question to understand the exceptions and requirements fully.