在交换机 vty 线路上输入transport input ssh 命令时会发生什么？ What happens when the transport input ssh command is entered on the switch vty lines?

A、交换机上的SSH客户端已启用。TheSSHclientontheswitchisenabled.
B、交换机需要用户名/密码组合才能进行远程访问。Theswitchrequiresausername/passwordcombinationforremoteaccess.
C、交换机需要通过专有客户端软件进行远程连接。Theswitchrequiresremoteconnectionsviaaproprietaryclientsoftware.
D、交换机和远程用户之间的通信是加密的。Communicationbetweentheswitchandremoteusersisencrypted.