The validity period of one of your driving licence classes has expired. What are the consequences of this?

The selected combination is correct because when the validity period of a driving licence class expires, the driving licence is no longer valid for that specific class, and it is indeed prohibited to drive motor vehicles that fall under this class. According to German traffic regulations, once the expiry occurs, you cannot use that driving licence class until it has been renewed or revalidated.

It's important to note that option three, which states that the licence may still be used for private journeys, is incorrect. In Germany, you cannot drive at all with an expired driving licence for that class, regardless of the nature of the journey. This regulation is in place to ensure road safety and accountability among drivers.