Which mirror helps monitor activities inside the bus?

The overhead inside rearview mirror is specifically designed to provide the driver with a clear view of what is happening inside the bus. This mirror is positioned above the front windshield and is crucial for monitoring passengers, especially children, ensuring their safety and security during transit. It helps drivers keep an eye on student behavior and allows for quick assessment of the interior environment without needing to turn around, which can distract from the road ahead.

In contrast, the other mirror options serve different purposes; side mirrors are primarily used to monitor the area surrounding the bus to detect vehicles or pedestrians approaching from the sides, while crossover mirrors are designed to eliminate blind spots and improve visibility to the front and sides. Convex mirrors widen the view but are not specifically aimed at monitoring interior activities. Thus, the overhead inside rearview mirror is the correct choice for this function.