A developer has written the following search function that you need to examine for any potential problems. What will the function return if the key value is not in the vector?

$```$

int myfunction$($vector& v$,$ int key$)$

$\{$

int index $=0$;

while $($index $$ v$.$size$()$ && key $!=$ v$[$index$])$

$\{$

if $($v$[$index$]!=$ key$)$

$\{$

index$++$;

$\}$

$\}$

return index;

$\}$

$```$

$0$

$-1$

v$.$size$()$

v$.$size$()-1$