what functionality is required on the Cisco ADSL router so the end-user connected to the Cisco ADSL router can access the Internet without entering a username and password?

Typical ADSL broadband Internet access requires a username and password to be entered on
end-user PC connected to the ADSL modem in order for the end user to gain access to the
Internet.if a Cisco ADSL router is used instead of an ADSL modem,what functionality is required
on the Cisco ADSL router so the end-user connected to the Cisco ADSL router can access the
Internet without entering a username and password?

A.
Route Bridge Encapsulation(RBE)

B.
PPPoA

C.
Integrated Routing and Bridging(IRB)

D.
AAA

E.
PPPoE client