Which protocol and port have been assigned by IANA for RADIUS authentication？（）

A.The MPLS header is 2 bytes，and the EXP field is 3 bits long.
B.The MPLS header is 1 byte，and the EXP field is 3 bits long.
C.The MPLS header is 4 bytes，and the EXP field is 3 bits long.
D.The MPLS header is 3 bytes，and the EXP field is 3 bits long.

A.RED randomly drops packets before the queue becomes full.
B.RED is always useful，without dependency on flow.
C.RED increases the drop rate as the average queue size increases.
D.RED has a per-flow intelligence.