Final answer:
When reversing a bus, a driver should use all mirrors to have the widest and most comprehensive view of their surroundings, ensuring maximum safety.
Step-by-step explanation:
When reversing your bus, you should use all of your mirrors. Doing so allows the driver to have the widest field of vision and to monitor all areas around the bus to ensure safety. The mirrors are designed to provide different angles and views; thus, using only one would limit the driver's awareness of the surrounding environment. It is important not only to rely on mirrors but also to be cautious and aware of any blind spots, pedestrians, other vehicles, and obstacles that may not be fully visible in the mirrors.