4. write a statement involving a pointer expression using the variables in this program which is ILLEGAL given your declared types. main() {int a, b, c; ??? ra; ??? rb; ??? rc; ??? rra; ??? rrb; ??? rrc; a = 1; b = 2; c = 3; ra = &a; rb = &b; rc = &c; ra = rb; rra = &rb; rc = *rra; rrc = rra; rc = &a; rrb = &rc; rb = &c; *ra = 4; *rb = *ra + 5; /* (*) */ printf ("%d %d %d ",a,b,c); printf("%d %d ", *ra, *rb); printf("%d %d %d ",**rra, **rrb, **rrc); }