The network administrator is adding a new spoke, but the tunnel is not passing traffic. What could cause this issue?

Refer to the exhibit.

The network administrator is adding a new spoke, but the tunnel is not passing traffic. What could cause this issue?
A . DMVPN is a point-to-point tunnel, so there can be only one spoke.
B . There is no EIGRP configuration, and therefore the second tunnel is not working.
C . The NHRP authentication is failing.
D . The transform set must be in transport mode, which is a requirement for DMVP
F . The NHRP network ID is incorrect.

Answer: C

Explanation: http://www.cisco.com/c/en/us/td/docs/ios/12_4/ip_addr/configuration/guide/hadnhrp.html#wp1055049