Refer to the exhibit. CE1 and CE2 cannot communicate through the service provider BGP peering is established between PE1 and PE2. IS-IS is the only routing protocol running in the service provider core. What step can be done to troubleshoot the issue?
A. Switch the IGPs running in the core from IS-IS to OSPF to support a Cisco MPLS TE tunnel from PE1 to PE2.
B. Configure BGP between CE and PE routers.
C. Confirm that IS-IS is running with metric-style narrow.
D. Verify the MPLS LSPs.
This is definitely not C. To me C state that metric-style should run, that is why you confirm it. Since MPLS-TE is used you must use metric-style wide not narrow. It should be D, if the LSPs are broken you will not have VPN connectivity assuming that PEs deliver MPLS VPNs. This question is very unclear