The correct command to change the ownership of the file doku.odt to a new owner named tux is chown tux doku.odt. This command uses the chown command, which stands for change owner, followed by the name of the new owner and the name of the file as arguments. The chown command allows you to change the user and/or group ownership of a given file, directory, or symbolic link12. The other options are incorrect because they use different commands or syntax that do not change the ownership of the file. For example:
Option A uses the chmod command, which stands for change mode, and is used to change the permissions of files and directories, not the ownership3.
Option B uses the newuser command, which is used to create a new user account, not to change the ownership of a file4.
Option D uses the transfer command, which is not a valid Linux command.
Option E uses the passwd command, which is used to change the password of a user account, not the ownership of a file5.