A.EBGP sessions between confederation sub ASs do not modify the next-hop attribute.
B.By default， iBGP sessions change the next-hop attribute learned from eBGP peers to self address.
C.By default， the next-hop attribute is not changed when a prefix is reflected by the route reflector
D.EBGP sessions between confederation sub ASs change the next-hop attribute to peer address.
E.By default， iBGP sessions preserve the next-hop attribute learned from eBGP peers.