how are the nonadjacent LDP neighbors discovered?

When nonadjacent LDP neighbors are used for implementing an MPLS traffic engineering
solution, how are the nonadjacent LDP neighbors discovered?

A.
using multicast CR-LSP (constraint-based LSP)

B.
using unicast CR-LSP (constraint-based LSP)

C.
using multicast LDP hello messages

D.
using unicast LDP hello messages

E.
using multihop MP-IBGP

F.
using multihop MP-EBGP