问题：

[单选] You are a network technician at Certpaper.com. Which description is correct when you have generated RSA keys on your Cisco router to prepare for secure device management？（）

A . You must then specify the general-purpose key size used for authentication with the crypto key generaters a general-keys modulus command.
B . You must then zeroize the keys to reset secure shell before configuring other parameters.
C . All vty ports are automatically enabled for SSH to provide secure management.
D . The SSH protocol is automatically enabled.