What must be done regarding vehicle hazard warning placards and orange panels under GB 13392 and the Provisions on the Administration of Road Dangerous Goods Transport (MOT Order 2013 No. 2, as amended) after a tank vehicle has discharged its hazardous payload and has been thoroughly cleaned, purged, and certified non-hazardous?

1. The hazard placards and orange identification panels must be removed or completely covered (遮盖或拆除)
2. The placards must remain permanently displayed for the lifetime of the truck
3. The placards must be painted over with fluorescent green spray paint
4. The driver must attach an extra 'Explosive' sign to celebrate successful discharge