A road sign in the IAAA Category E bank forbids the entry of motor vehicles with trailers, with which official exception?

1. No exception; every trailer, including a single-axle trailer and a semi-trailer, is banned
2. The entry of motor vehicles with trailers is forbidden, with the exception of semi-trailers and one-axle trailers
3. Only combinations over 24 t are banned
4. Only buses with luggage trailers are banned