BGP address families are used to configure which three route exchange mechanisms? (Choose three)

A.
Propagating Internet routes.

B.
VPNv4 routes that are propagated across an MPLS/VPN backbone.

C.
P-router to P-router routes that are propagated across an MPLS/VPN backbone.

D.
PE-CE routing protocol to exchange VPN routes between provider edge routers and customer edge routers.

Explanation:

According to the "Implementing Cisco MPLS" Student Guide (Text Part Number:
97-1154-01) Volume 2, version 1.0, page 8-31.
BGP address families: The BGP process in a MPLS VPN-enabled router performs 3 separate tasks:
– Global BGP routes(internet routing) are exchanged as in traditional BGP setup.
– VPNv4 prefixes are exchanged through MP-BGP.
– VPN routes are exchanged with CE routers through per-VRF EBGP sessions. Address families (routing contexts) are used to configure these three tasks in the same BGP process(because only one BGP process can be configured per router), and the routing contexts (called address families from the router configuration perspective) are used to configure all three independent route exchange mechanisms.