Refer to the exhibit.

What would be the security risk when you are using the above configuration?

A.
The locally configured users would override the TACACS+ security policy.

B.
It would be impossible to log in to the router if the TACACS+ server is down.

C.
The default login policy would override the TACACS+ configuration.

D.
If the TACACS+ server failed, no authentication would be required.

Explanation:
You could use the aaa authentication login default tacacs+ enable command to specify that if your
TACACS+ server fails to respond, you can log in to the access server by using your enable
password. If you do not have an enable password set on the router, you will not be able to log in to
it until you have a functioning TACACS+ UNIX daemon or Windows NT or Windows 2000 server
process configured with usernames and passwords. The enable password in this case is a lastresort authentication method. You also can specify none as the last-resort method, which means
that no authentication is required if all other methods failed.