Final answer:
Drivers are required to stop within 20 feet of a school bus with flashing lights to ensure the safety of children crossing the road.
Step-by-step explanation:
You must stop within 20 feet of an oncoming school bus with flashing lights. This is a critical safety rule to protect children who may be crossing the road when they embark or disembark from a school bus.
Laws regarding stopping distances for oncoming school buses with flashing lights can vary by jurisdiction. However, a common standard in many places is to stop within 20 feet of a school bus with flashing lights. Therefore, the correct answer is: B) 20 feet.
It's important to be aware of and adhere to local traffic laws, as they can vary. Always follow the specific regulations and guidelines in your area regarding school bus safety.