A load contains Division 5.1 oxidizer and Class 3 flammable liquid. Why must the driver check segregation rules instead of relying on package strength alone?

1. Strong packages can still leak in a crash, and incompatible materials may intensify fire or reaction hazards
2. Strong packages always make segregation unnecessary
3. Oxidizers and flammables are never regulated when packaged
4. Segregation applies only to rail cars