Final answer:
You must not pass a school bus at any speed when it is stopped and dropping off or picking up students, as it is illegal to pass a school bus with flashing red lights and an extended stop arm.
Step-by-step explanation:
The appropriate speed at which you can pass a school bus that is dropping off or picking up students would actually be zero mph, as passing a stopped school bus that has its flashing red lights activated and stop arm extended is illegal in many areas. Drivers are required to stop on both sides of the road when a school bus is loading or unloading children. This law is in place to ensure the safety of students as they enter and exit the bus. The exact laws can vary by state or country, but generally, you must always stop for a school bus with active safety signals and may only proceed if the bus begins to move again, or the bus driver signals to you that it is safe to pass. It is important to always remain vigilant for the flashing red lights of a school bus, to check local laws for specific guidelines, and to never pass a school bus when it is unsafe to do so.