An engineer must enable a login authentication method that allows a user to log in by using local authentication if all other defined authentication methods fail. Which configuration should be applied

The `local-case` keyword is not a valid option for `aaa authentication login` command to specify local authentication fallback, and the repeated `aaa` keyword at the end is syntactically incorrect.

The `none` keyword, if reached, would allow login without any authentication, which does not meet the requirement of falling back to *local authentication* and poses a significant security risk. Also, `aaa` is missing at the start of the command.

While `group radius local enable` is syntactically valid and enables local fallback, TACACS+ (used in option D) is generally preferred over RADIUS for device administration on Cisco platforms due to its separate AAA services and more extensive command authorization capabilities, making D a more commonly recommended solution for administrative access.

The command `aaa authentication login CONSOLE group tacacs+ local enable` configures a login authentication method list. It first attempts authentication using the TACACS+ server group, and if that fails, it falls back to the local user database. The `enable` keyword allows a further fallback to the device's enable password.