How could you check for potential MTU size issues on the path taken by a PE-to-PE LSP?

A.
Because MPLS packets are label switched, MTU problems can only be detected by the user
applications.

B.
Use the ping vrf command with packet size set to the largest MTU along the path and DF bit set
from the local PE-router to ping the remote PE-router.

C.
Use the ping vrf command with packet size set to the smallest MTU along the path and DF bit
set from the local PE-router to ping the remote PE-router.

D.
Because MPLS packets are label switched, packets are automatically fragmented and
reassembled by the PE-routers. Therefore, there are no potential MTU issues.