What must be visible for the driver to check that lights are functioning properly?

• A. Rearview mirror
• B. Side mirrors
• C. Window overlooking the street
• D. Driver's display panel

Answer: (C)

For a driver to effectively check that the lights are functioning properly, the window overlooking the street is crucial. This visibility allows the driver to observe the lights, including headlights, taillights, and turn signals, while someone else assists by activating them. It's essential for ensuring that all lights are operational from the outside perspective, as the driver needs to verify that lights illuminate correctly and are visible to other road users.

While other options such as the rearview and side mirrors or the driver's display panel may provide some information about the vehicle's overall operation, they do not allow for direct observation of the external lighting systems. Hence, the window overlooking the street is the most essential for confirming that all lights on the bus are functioning as intended.