How can you change a user's username in a Linux system for a married employee?

To change a user's username in a Linux system, the command utilized is usermod -l new_username old_username. This structure clearly indicates that you are specifying the new username followed by the current (old) username.

In the correct choice, the command usermod -l kjones kscott effectively renames the user kscott to kjones. The -l option is what allows you to change the login name of the user to the new specified one, ensuring that all related files and directories can be updated accordingly, facilitating a seamless transition to the new username for the married employee.

Other choices either misplace the order of parameters or use incorrect options. For instance, using -u instead of -l implies a change in the user ID rather than the username, which is not the objective here. Therefore, the correct syntax and option lead to a successful username change in the system, making option C the appropriate choice.