What must be done to a school bus when transporting adults for a non-school function?

When transporting adults for a non-school function, it is required to cover the flashing lights on the school bus. This is important because the flashing lights are specifically designed for school-related activities, signaling to other vehicles that children may be present and to stop for boarding or disembarking. Covering the flashing lights eliminates potential confusion about the bus being in a school-related context, thus ensuring safety and compliance with traffic regulations.

The other options may not accurately represent the requirements for non-school transportation functions. For instance, removing the stop sign or unmarking the school bus identification may not be mandated or practical in every situation, and focusing on covering the flashing lights is the primary concern to signal that the bus is not engaged in its typical role of transporting school students.