BGP is used as the CE-PE routing protocol in an MPLS VPN. The customer routes are successfully propagated from the CE router to the ingress PE router, but they are not showing up on the egress PE router. What is the most likely cause of the problem?

A.
There is a BGP-to-MPBGP redistribution error on the ingress PE router.

B.
There is a MPBGP-to-BGP redistribution error on the egress PE router.

C.
One of the P routers is performing route summarization, breaking the path between the ingress and the egress PE routers into two LSPs.

D.
RTs attached to the CE routes exported by the ingress router are not matched by at least one of the import RTs on the egress PE router.

E.
A route reflector is used to propagate the routes from the ingress PE router to the egress PE router, thus breaking the LSP.