單項(xiàng)選擇題Typical ADSL broadband Internet access requires a username and password to be entered on end-userPC connected to the ADSL modem in order for the end user to gain access to the Internet.if a Cisco ADSLrouter is used instead of an ADSL modem，what functionality is required on the Cisco ADSL router so theend-user connected to the Cisco ADSL router can access the Internet without entering a username andpassword？（）

A.PPPoA
B.Route Bridge Encapsulation（RBE）
C.PPPoE client
D.Integrated Routing and Bridging（IRB）
E.AAA