All the seats on your bus are equipped with the prescribed safety belts. You are driving in non-regular traffic. What is correct?

You answered correctly. When all seats in your bus have the required safety belts and you are driving outside of regular line service, both you and your passengers are required by law to wear seat belts. In addition, as the driver, you must inform your passengers that they have to fasten their safety belts. The rule applies regardless of whether you are driving inside or outside built-up areas. Not wearing a seat belt is only allowed in certain special exemptions, which do not apply here. Knowing this ensures you help keep everyone safe and comply with German road laws.