Which Layer 3 VPN scaling mechanism allows PE3 to begin receiving Customer B routes?

Given the existing operational network shown in the exhibit, you now want to add a remote site for Customer B to the PE3 router. This change should not have an effect on the existing BGP sessions between the PE routers.Which Layer 3 VPN scaling mechanism allows PE3 to begin receiving Customer B routes?

A.
route origin

B.
route refresh

C.
route reflection

D.
route target filtering