Which option is used in the Samba configuration file to set which files and directories are neither visible to or accessible by the clients?

`mangle names` is used to convert long filenames to short 8.3 format for compatibility with older Windows clients, not to hide or block access to files.

`hide dot files` specifically hides files and directories that start with a dot (`.`) from directory listings, but these files might still be accessible if the client knows the path.

`hide special files` is not a standard Samba option for general file hiding; options like `hide unreadable` or `hide unwriteable` address specific access conditions.

`hide files` makes files invisible in directory listings but still allows access if the full path is known, which is less restrictive than `veto files`.

The `veto files` option in the Samba configuration (`smb.conf`) is used to specify a list of files and directories that clients cannot see or access, effectively making them invisible and unavailable. This provides a strong level of protection for sensitive or internal server files, behaving as if they do not exist for the client.