An engineer is troubleshooting a new DMVPN setup on a Cisco IOS router. After the show crypto isakmp sa command is issued, a response is returned of "MM_NO_STATE." Why does this failure occur?
A. The ISAKMP policy priority values are invalid.
B. ESP traffic is being dropped.
C. The Phase 1 policy does not match on both devices.
D. Tunnel protection is not applied to the DMVPN tunnel.