Which of the following is a function of a backing guide?

The function of a backing guide primarily involves surveying the area around the vehicle to ensure it can safely reverse without encountering obstacles or hazards. This role is crucial during backing maneuvers, particularly in operational environments where visibility may be limited. A backing guide assists the driver by providing visual cues or directions, mitigating the risk of collisions with other vehicles, personnel, or obstacles.

While directing traffic, controlling speed, and starting the engine are all important functions in a vehicular context, they do not pertain directly to the specific role of a backing guide. Directing traffic generally involves broader traffic management scenarios, controlling speed is related to operational safety and vehicle handling, and starting the engine is a basic operational task that is not linked to the backing process.