E22 Answer

8 

Comments: There is a single external entity that corresponds to the identifier x. The keyword extern is not needed in file fileC.c, but makes clear that its x is external.

/* --- fileA.c --- */
int x = 8



/* --- fileB.c --- */
foo()
{
  int x;
  x = 99;
}



/* --- fileC.c --- */
extern int x;
main()
{
  foo();
  printf("%d\n", x );
  system("pause"); 
}