What activates the stop arms and overhead red warning lights after the bus has stopped?

The activation of the stop arms and overhead red warning lights after the bus has come to a stop is triggered by opening the entrance door slightly. This safety feature is designed to alert other drivers that the bus is unloading or loading passengers, particularly children, and emphasizes the importance of visibility and safety during this critical time. When the entrance door is opened, the bus's warning systems engage automatically, which serves to inform surrounding traffic to stop and ensure that any pedestrians or students boarding or disembarking are protected from oncoming vehicles.

The other options do not serve this specific function in the same manner. For example, pressing a button or using a manual switch does not typically initiate the automatic warning system in modern buses, as they rely on the door mechanism for this purpose. Sounding the horn, while useful for alerting drivers in certain situations, does not trigger the warning lights or stop arms and is more intended for communication in traffic situations rather than for engaging safety features during pickup or drop-off. Understanding this mechanism helps reinforce safe practices for school bus operations and enhances the safety of students.