Refer to the exhibit. Which two statements about the AAA configuration are true?（）

• A、A good security practice is to have the none parameter configured as the final method used to ensure that no other authentication method will be used.
• B、If a TACACS+ server is not available， then a user connecting via the console port would not be able to gain access since no other authentication method has been defined.
• C、If a TACACS+ server is not available， then the user Bob could be able to enter privileged mode as long as the proper enable password is entered.
• D、The aaa new-model command forces the router to override every other authentication method previously configured for the router lines.
• E、To increase security， group radius should be used instead of group tacacs+.
• F、Two authentication options are prescribed by the displayed aaa authentication command.