Which statement about loading equipment and the vehicle engine is correct?

1. The engine may run only if it is needed to drive pumps or other equipment used for the loading or unloading operation; otherwise it is switched off
2. The engine must always run to keep ABS pressurised while people work around open packages
3. A sparking metal inspection lamp may be used in the vapour space of a Class 3 compartment
4. Smoking is allowed on the tail-lift because it is outside the cargo box