Final answer:
When approaching a school bus with flashing lights and an extended stop sign, the correct action is to stop completely at least 20 feet away from the bus to ensure the safety of crossing children.
Step-by-step explanation:
If you are approaching a school bus or a school pupil transport vehicle with its lights flashing and a stop sign extended, the correct action to take is to come to a complete stop at least 20 feet away from the bus. This is a safety measure to protect school children who may be crossing the road. Therefore, the correct answer is A) Come to a complete stop at least 20 feet away from the bus. Answers such as B) Slow down and proceed with caution, C) Honk your horn to alert the driver and continue driving, and D) Speed up and pass the bus quickly to avoid delays, are incorrect and could result in dangerous situations for pedestrians and violations of traffic law.