Network topology exhibit

Liberal label retention and unsolicited downstream distribution is being used in the frame-mode MPLS network shown in the exhibit. The best to network X as defined by the IGP for network is Certkiller 1- Certkiller 2- Certkiller 4- Certkiller 5. What will Router Certkiller 3 and router Certkiller 4 add to their LIB regarding network X?

A.
Both routers will add it to their LIB.

B.
Both routers will ignore it.

C.
Router Certkiller 3 will add the label to its LIB. Router Certkiller 4 will ignore it.

D.
Router Certkiller 4 will add the label to its LIB. Router Certkiller 3 will ignore it.