What is the rule regarding the mixed loading of Class 1 (explosives) and Class 3 (flammable liquids) on the same vehicle?

1. It is generally prohibited, with very few exceptions for specific compatibility groups
2. It is permitted if the total points are under 1000
3. It is permitted if gasoline and fireworks are in separate compartments
4. It is allowed as long as the cargo is covered by a tarpaulin