The do_stuff file has been created so that when users execute it, the GID of the process that is created is the same as the group owner of the file, but the owner of the process is the user that started it.
Which command sets the group ID on this file?

A.
chmod 6555 do_stuff

B.
chmod 2544 do_stuff

C.
chmod 2555 do_stuff

D.
chmod 2444 do_stuff