What is the root cause of this issue?

A Layer 3 VPN customer opened a case that reports connectivity loss with remote sites. An operations engineer realized this connectivity loss happened after the LDP label filtering was applied.

What is the root cause of this issue?
A . Labels were not allocated for the PE, P and RR physical interfaces
B . Labels were not allocated for the PE loopbacks
C . Labels were not allocated for the CE loopback and physical interfaces
D . Labels were not allocated for the P loopbacks
E . Labels were not allocated for the PE, P, and RR loopbacks
F . Labels were not allocated for the P and PE physical interfaces

Answer: B