How must hand luggage brought into the passenger compartment of a touring coach be safely stored?

1. Stacked in the centre aisle where it can be reached quickly
2. In front of the emergency door release valves and the fire extinguisher, where it is easy to see
3. On the seats beside passengers, so nothing is above head height
4. In the overhead racks or under the seats, leaving the centre aisle, stairwells and all emergency exits completely clear