Which of the following best describes downstream unsolicited label distribution?

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

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

An LSR propagates a label mapping downstream for a FEC, only if it has a label mapping for the FEC next-hop.

An LSR will only distribute a label for a FEC when it has been requested to do so.