Refer to the exhibit.

The correct design uses IPv4 unicast for Company A and Company B and VPNv4 in the shared core. In an MPLS Layer 3 VPN architecture, customer edge routing toward the provider edge commonly uses the ordinary IPv4 unicast address family. The PE router then places the learned customer routes into the appropriate VRF. Across the shared provider core, MP-BGP carries those customer routes as VPNv4 prefixes by adding route distinguishers, which keep identical or overlapping customer prefixes unique. Route targets then control which VRFs import or export each route. Cisco describes this VRF and VPNv4 model as the mechanism that prevents one VPN customer from learning another customer’s prefixes while sharing the same provider backbone. VPNv4 is not normally used directly between the customer networks and their CE-facing sessions. Therefore, the customer sides use IPv4 unicast, and the shared core uses VPNv4 to preserve separation. Reference topics: MPLS Layer 3 VPN, MP-BGP VPNv4, VRF, route distinguisher, route targets, customer route isolation.