What is the correct Cisco IOS XR command to configure an autonomous system number 1000 for
BGP and to support IPv4, IPv6, and unicast routing?

A.
router bgp 1000
address-family ipv4 unicast
!
address-family ipv6 unicast
!!

B.
router bgp 1000
neighbor 1.1.1.1 remote-as 2000
address-family ipv4 unicast
!
address-family ipv6 unicast
!!

C.
router bgp 1000
address-family vpnv4 unicast
!
address-family vpnv6 unicast
!!

D.
router bgp 1000
neighbor 1.1.1.1 remote-as 2000
address-family vpnv4 unicast
!
address-family vpnv6 unicast
!!

Explanation: