Which keyword did the administrator leave off of the AAA configuration?

A network administrator set-up AAA on a new router. While the TACACS server was down for
maintenance, the administrator was still unable to login with the backup password. Which keyword did the administrator leave off of the AAA configuration?
A. The keyword local is missing from the AAA authentication login statement.
B. The keyword local is missing from the AAA authentication exec statement.
C. The keyword default is missing from the login authentication.
D. The command line privilege level 0 is missing from the VTY configuration.