What is the minimum distance required to stop behind a school bus when its flashing lights are on?

Answer: C — 20 feet

The minimum distance required to stop behind a school bus when its flashing lights are on is 20 feet. This regulation is in place to ensure the safety of children boarding or exiting the bus. When the bus's lights are flashing, it indicates that children are likely in the vicinity and may be crossing the road. Stopping at this distance gives enough space for children to safely move around the bus and reduces the risk of accidents. Following this guideline not only protects children but also ensures that drivers comply with traffic laws designed to ensure safety in school zones. It's crucial for drivers to remain vigilant and adhere to this and similar regulations to foster a safe environment for students.