A programmer has written the following function for implementing the merge sort algorithm, but is not sure if the function is correct.

void merge$\_$sort$($vector& a$,$ int from, int to$)$

$\{$

if $($from $==$ to$)\{$ return; $\}$

int mid $=($from $+$ to$)/2$;

$//$ Sort the first and the second half

merge$\_$sort$($a$,$ from $+1,$ mid$)$;

merge$\_$sort$($a$,$ mid $+1,$ to$)$;

merge$($a$,$ from, mid, to$)$;

$\}$

What is true about this merge$\_$sort function?

Question $10$ options:

It is a recursive function that will never terminate.

The call to merge is not necessary.

There is a mistake in the parameters passed to the recursive calls to merge$\_$sort.

The merge$\_$sort function works perfectly as written.