Which command would delete a user account and all associated files for the user Bob Smith?

The command that would effectively delete a user account and all associated files for the user Bob Smith is correctly identified, as it utilizes the appropriate syntax for removing a user. When forming the command, the “userdel” command is specifically meant for deleting user accounts in Unix-like operating systems.

The “-r” option is key in this context as it signifies that the user's home directory and mail spool, along with any other associated files, should also be removed. Therefore, while the initial command suggests merely a deletion of the user account itself, it does not ensure the removal of associated files, which is critical in this scenario.

Commands involving "userdel -h" and "userdel -Z" do not serve the purpose of deleting a user and their associated files, as they have different implications. The “-h” option is not a standard option for user deletion, and "userdel -Z" typically relates to SELinux user context management rather than user account deletion.

Thus, understanding the functionality of the “-r” option in conjunction with the “userdel” command is crucial for ensuring that the user account and their associated files are completely removed, aligning well with security practices of keeping a clean system environment.