When can you legally pass a school bus on an undivided roadway?

Passing a school bus on an undivided roadway is strictly regulated to ensure the safety of children. The correct answer is when the red lamps are not flashing. This indicates that the bus is either not loading or unloading passengers, and it is safe to continue driving.

When the red lights are flashing, it signifies that children are either getting on or off the bus, and motorists are required to stop to prevent any potential accidents. Therefore, understanding the behavior of the bus signals is crucial for any driver when encountering a school bus. This rule is in place to protect the most vulnerable road users, ensuring that they can safely cross the street.

The other options suggest conditions under which it might seem permissible to pass a school bus, but they do not adhere to the safety regulations mandated for driving near school buses. Hence, knowing and adhering to these flashing light signals is essential for safe driving practices around school zones.