Final answer:
When encountering a stopped school bus with flashing red lights, you must stop your vehicle at least 20 feet away from the bus to ensure the safety of boarding or alighting students.
Step-by-step explanation:
If you encounter a stopped school bus with red lights flashing, you must stop your vehicle at least 20 feet from the bus. This rule is designed to keep children safe as they enter and exit the bus, providing them with a safety zone that drivers cannot enter. It's important to always follow this rule whenever you see a school bus stopped with red lights flashing to ensure the safety of students.