If an operator needs to back up the bus, what is the recommended action?

The recommended action of using a responsible person, backing up slowly, and sounding your horn is vital for ensuring safety when an operator needs to reverse the bus. By having a responsible person, such as a ground guide, assist in this maneuver, the operator significantly enhances situational awareness, as the guide can see areas that may be blind spots for the driver.

Backing up slowly allows the operator to maintain control of the vehicle and provides time to react if an obstacle is encountered. Sounding the horn serves as an audible warning to pedestrians and other vehicles, making them aware of the bus's movement. This combination of actions contributes to a safer environment for everyone, including passengers on the bus.

In contrast, backing up quickly may lead to accidents or collisions, while not using any signals could create confusion and increase the risk of an incident. Additionally, relying solely on mirrors does not provide a complete view of the area behind the bus, which can be unsafe. Therefore, option C embodies the best practices for safely backing up a bus.