Which vehicles must carry approved warning devices according to the regulations?

The requirement for vehicles to carry approved warning devices is particularly relevant for those with a larger passenger capacity. Vehicles designed to transport more than 10 passengers are classified as commercial or passenger transport vehicles and are subject to stricter safety regulations. This is due to the increased responsibility that comes with transporting more individuals, which necessitates enhanced safety measures, including the use of warning devices.

These warning devices serve critical functions, such as alerting other road users in case of emergencies or breakdowns, which is especially important when a larger number of passengers are involved. This regulation ensures not only the safety of passengers but also contributes to the overall safety on the roads for all users.

In contrast, the other options reference varying types of vehicles and specific attributes that do not universally mandate the inclusion of approved warning devices. For example, vehicles with a maximum speed under 50 km/h do not inherently require such devices unless further specified by additional regulations. Similarly, commercial vehicles with a width under 2.3 m and all passenger vehicles do not automatically fall under the same requirements for carrying warning devices unless they meet specific criteria that align with the regulations, which typically prioritize larger capacity vehicles.