Which of the following commands can be used to search for the executable file foo when it has been placed in a directory not included in $PATH?

`apropos` searches the man page database for keywords, not the filesystem for executable files.

`which` specifically searches for executable commands only within the directories listed in the user's `$PATH` environment variable.

The `find` command is capable of recursively searching specified directories for files based on various criteria, such as name, type, and permissions, making it ideal for locating an executable file not present in the system's `$PATH`.

`query` is not a standard Linux command for searching for files on the filesystem.

`whereis` locates source, binary, and man page files for a command, primarily by searching standard system locations, not arbitrary directories outside `$PATH`.