Which of following is true about the reverse$\_$string function used in solving the problem of reversing a string?

string reverse$\_$substring$($string str$,$ int start, int end$)$

$\{$

if $($start $>=$ end$)$

$\{$

return str;

$\}$

char ch $=$ str$[$start$]$;

str$[$start$]=$ str$[$end$]$;

str$[$end$]=$ ch;

return reverse$\_$substring$($str$,$ start $+1,$ end $-1)$;

$\}$

string reverse$\_$string$($string str$)$

$\{$

return reverse$\_$substring$($str$,0,$ str$.$length$()-1)$;

$\}$

Question $5$ options:

The reverse$\_$string function is a recursive function.

The reverse$\_$string function is an iterative function.

The reverse$\_$string function uses reverse$\_$substring as a helper function.

The reverse$\_$substring function uses reverse$\_$string as a helper function.