How should a driver interpret the tunnel restriction code '(B/D)' shown on the transport document for a particular substance?

1. The load is prohibited in Category B tunnels in summer, and Category D in winter
2. The restriction is Category B if carried in tanks, but Category D if carried in packages
3. The restriction is Category D if carried in tanks, but Category B if carried in packages
4. The vehicle is permitted in all tunnels except those in Dublin