Consider the following JavaScript skeletal program:

$//$ The main program

var x;

function sub$1()\{$

Problem Set $253$

var x;

function sub$2()\{$

$...$

$\}$

$\}$

function sub$3()\{$

$...$

$\}$

Assume that the execution of this program is in the following unit order:

main calls sub$1$

sub$1$ calls sub$2$

sub$2$ calls sub$3$

a$.$ Assuming static scoping, in the following, which declaration of x is the

correct one for a reference to x$?$

i$.$ sub$1$

ii$.$ sub$2$

iii. sub$3$

b$.$ Repeat part a$,$ but assume dynamic scoping.