What must you do when approaching a stopped emergency vehicle with flashing lights?

Answer: C — Slow down and pass slowly

When approaching a stopped emergency vehicle with flashing lights, it is crucial to slow down and pass carefully. This practice enhances safety for both the emergency personnel working at the scene and the driver passing by. By reducing speed, a driver can better assess any potential hazards and respond appropriately to the situation. Additionally, many states, including Minnesota, have "move over" laws requiring drivers to either move over one lane away from the emergency vehicle, if possible, or slow down significantly when passing. This not only ensures the safety of the emergency responders but also helps maintain a safe environment on the road for all involved.