WhichofthesestatementsbestdescribesthemajordifferencebetweenanIPv4－compatibletunnelanda6to4tunnel?()

A.AnIPv4-compatibletunnelisastatictunnel，butan6to4tunnelisasemiautomatictunnel.

B.ThedeploymentofaIPv4-compatibletunnelrequiresaspecialcodeontheedgerouters，buta6to4tunneldoesnotrequireanyspecialcode.

C.AnIPv4-compatibletunnelistypicallyusedonlybetweentwoIPv6domains，buta6to4tunnelisusedtoconnecttoconnecttwoormoreIPv6domains.

D.ForanIPv4-compatibletunnel，theISPassignsonlyIPv4addressesforeachdomain，butfora6to4tunnel，theISPassignsonlyIPv6addressesforeachdomain.