Refer to the exhibit.

Routers R1 and R2 have exchanged label binding information. What is preventing the labels from
populating the MPLS forwarding table?

A.
MTU on the serial interface cannot accommodate labels.

B.
Cisco Express Forwarding is not running.

C.
The MPLS label distribution protocol is mismatched.

D.
Inbound access list 100 is applied on the serial interface.