What should a commercial driver do when encountering a long line of slow-moving traffic in a mountain pass tunnel?

1. Maintain a minimum 50-metre spacing from the vehicle in front, keep low-beam headlights on, switch cabin ventilation to recirculate, and never attempt to overtake
2. Tailgate closely to avoid letting other vehicles merge
3. Turn off headlights to save battery power
4. Weave between lanes to move forward faster