When can the authorities order a bus driver to undergo a fitness assessment?

The selected combination is correct because it encompasses all the circumstances under which authorities can mandate a fitness assessment for a bus driver. According to German traffic regulations, these assessments are necessary to ensure that drivers maintain a safe standard of driving.

1. Serious violations of road traffic regulations may indicate a lack of judgment or risky behavior, warranting an evaluation of the driver's fitness.
2. Committing a serious road traffic offense, such as causing accidents or endangering other road users, further justifies the need for an assessment to evaluate the driver's capacity to operate a vehicle safely.
3. Indications of a high potential for aggression suggest that a driver may pose a risk to others, making it essential to assess their psychological readiness and temper when handling a vehicle.

Together, these factors ensure a comprehensive approach to driver safety, reflecting the importance of each option in maintaining road safety standards.