If a vehicle carrying dangerous goods is involved in an incident resulting in a minor chemical leak, what immediate action must the driver take according to the Instructions in Writing (ADR 5.4.3.4)?

1. Drive at maximum speed to the nearest customer warehouse to unload
2. Open all cargo doors to allow fumes to disperse while driving
3. Apply the braking system, stop the engine, isolate battery if safe, put on high-visibility clothing, and notify emergency services
4. Attempt to wash the chemical down a storm drain with tap water