Under GB 7258-2017 and passenger transport operating standards, how must passenger luggage and carry-on items be managed inside a passenger bus?

1. Luggage may be stacked in the central aisle as long as passengers can step over it
2. All large luggage must be stowed in the dedicated lower luggage compartment, and aisles and emergency exits must remain completely clear of obstructions
3. Luggage may be placed in front of emergency exit doors if tied down with bungee cords
4. Luggage may be stacked on empty passenger seats up to the ceiling level