What is a key component to ensure passenger safety during a trip?

Ensuring the seatbelts are functional is crucial for passenger safety during a trip. Seatbelts are fundamental safety devices designed to restrain passengers in the event of a sudden stop or collision, significantly reducing the risk of injury. By confirming that all seatbelts are in working condition before departure, the driver actively promotes the safety of passengers, ensuring compliance with safety regulations and fostering a secure environment throughout the journey.

The other options, while important in their respective contexts, do not address safety in the same direct way. For instance, checking the exterior of the bus for scratches does not contribute to passenger safety; rather, it is more about the bus's aesthetic and surface condition. Maintaining a clean driver’s seat, while important for comfort and operational efficiency, does not impact passenger safety directly. Similarly, improving audio systems may enhance the travel experience but does not affect the safety measures necessary for passengers during the trip.