What is the primary danger when an ambulance driver (Class A2 license) operates with emergency lights and sirens?

1. The siren drains the engine oil
2. Other drivers and pedestrians may panic, fail to hear the siren due to sound-insulated cabins or loud music, or react unpredictably; the ambulance driver must always exercise extreme defensive caution and verify that intersections are clear before crossing against red lights
3. Sirens make the ambulance completely invisible
4. Emergency lights stall oncoming vehicle engines