What should you do if you are approaching a school bus that is stopped with its red lights flashing?

Answer: B — Reduce speed and pass with care

When a school bus has its red lights flashing, it means that the bus is stopped and children are either boarding or exiting the bus. This is an indicator that caution is needed as children may be crossing the street. Option A, taking a detour, is not an appropriate course of action as it may lead to further delays and potentially miss the school bus stop sign altogether. Option C, applying brakes firmly, is not the best option as it may cause sudden and abrupt stopping, potentially causing an accident. Option D, speeding up and quickly passing the school bus, is not a safe choice as it may endanger the children, other drivers, and yourself. Therefore, the best course of action is to reduce speed and pass with care to ensure the safety of children and yourself.