Final answer:
You must stop for a school bus with flashing red lights and a stop arm extended, staying stationary at least twenty feet away until the bus deactivates its signals and retract the stop arm.
Step-by-step explanation:
It is illegal to pass from either direction when the bus displays flashing red lights and the stop arm extends from the left side. You must stop at least twenty feet from the bus. You must remain stopped until the lights are turned off and the stop arm is folded in. In this scenario, the most appropriate action to take is to stop moving and become stationary until it is safe and legal to proceed. Doing so ensures the safety of children who may be entering or exiting the bus and is also in compliance with traffic laws.