According to MOT Order 2021 No. 16 (Regulations on Cruising Taxi Operations), which sign must a cruising taxi driver display when unable to take passengers due to refueling, meal breaks, or shift handovers?

1. A 'Special Hire' (专车) display sign
2. A 'Shift Handover' (交接班) or 'Out of Service' (暂停服务) sign
3. A 'Hired' (有客) sign while keeping the cabin empty
4. Turning off all vehicle headlights and interior lights