Assume the following JavaScript program was interpreted using static$-$scoping rules.

var x ;

function sub$1()\{$

document.write$("$x $="+$ x $+"")$;

$\}$

function sub$2()\{$

var x;

$x=8$;

sub$1()$;

$\}$

$x=10$;

sub$2()$;

What value of $x$ is displayed in function sub$1?$

$0$

$8$

$10$

$18$