Which two statements about queuing mechanisms are true？ （）

• A、FIFO queuing is only appropriate for slower serial interfaces
• B、weighted fair queuing is the default queuing mechanism used for all but slower than E1 rate interfaces
• C、only one queuing mechanism type can be applied to an interface
• D、weighted fair queuing does not require the configuration of access lists to classify traffic  
• E、flow-based weighted fair queuing provides for queues to be serviced in a round-robin fashion