read the coreutils source code, i don't find one struct define

[Crazy good]

Hello:
i'm come from China,when read the coretils source code,i don't find  option
struct define . well, my English is bad.....

FOR example:
static struct option const long_opts[] =
{
  {"force", no_argument, NULL, 'f'},
  {"interactive", optional_argument, NULL, INTERACTIVE_OPTION},

  {"one-file-system", no_argument, NULL, ONE_FILE_SYSTEM},
  {"no-preserve-root", no_argument, NULL, NO_PRESERVE_ROOT},
  {"preserve-root", no_argument, NULL, PRESERVE_ROOT},
}

----the struct option i don't find any file define
please tell me  where is option  struct define

           Thank you very much

              😀😀