Which of the variables defined could potentially be printed on line $8?$

$1$: x $=5$

$2$: def foo$($n$)$:

$3$: y $=$ n

$4$: def bar$()$:

$5$: z $=4$

$6$: return z

$7$: x $=$ bar$()$

$8$: print$($VARIABLE$)$