Which BGP extended community is used to control the distribution of VPN routing information and
to identify routers that may receive a set of routes that carry the community?

A.
SOO

B.
RT

C.
opaque

D.
route origin

E.
RD

Explanation:
http://blog.initialdraft.com/archives/1537/
Route Target is a 64-bits BGP community used for tagging prefixes. When exporting prefixes from
the VRF, we add to the prefixes a Route-Target community, so when the PE in the remote site has
to import prefixes into the VRF, it can easily identify which prefixes to import.