In the ACT, when must a heavy vehicle driver use high-beam headlights, and what is required when another vehicle approaches?

1. High beam can be used at all times, day and night
2. High beam is used on unlit roads when no vehicles are within 200 metres ahead; it must be switched to low beam when an oncoming vehicle approaches within 200 metres
3. High beam must always be used at night regardless of other traffic
4. High beam is forbidden for heavy vehicles