What should the bus driver do immediately if the automatic engine compartment fire alarm triggers while driving on a motorway?

1. Accelerate to reach the service area 15 km ahead
2. Pull over safely and stop, open all doors and get the passengers out at once, switch off the engine, and call the emergency services
3. Ignore the alarm as long as no smoke is visible in the mirrors
4. Continue at reduced speed to the next motorway exit so the bus is off the carriageway