Given the below code snippet :

interface Test $\{$

int aMethod$($String s$)$;

$\}$

Which of the following is a valid statement?

Pick ONE option

$3Aa=a$ a$.$length$()$;

$4$ String $s$

$5$ A $s="2"->$ Integer.parselnt$($s$)$;

$6$

$Ax=y\{$ return $y_i\}$;