Which of the following statements best describes downstream unsolicited label distribution?

A. An LER may answer requests for label mappings immediately, without waiting for a label mapping from the next-hop.

B. An LER may advertise label mappings to all peers for which it might be a next-hop for a given FEC.

C. An LER propagates a label mapping downstream for a FEC. only if it has a label mapping for the FEC next-hop.
D. An LER will only distribute a label for a FEC when it has been requested to do so.