Identify the correctly constructed ALTER TABLE statement to add a UNIQUE constraint to the column student$\_$number with the constraint name student$\_$number$\_$unique on the table called 'student'.

ALTER TABLE student ADD CONSTRAINT student$\_$number UNIQUE $($student$\_$number$\_$unique$)$;

ALTER TABLE student ADD CONSTRAINT student$\_$number UNIQUE $($student$\_$number$)$;

ALTER TABLE student ADD CONSTRAINT student$\_$number$\_$unique UNIQUE $($student$\_$number$)$;

ALTER TABLE student ADD UNIQUE student$\_$number CONSTRAINT $($student$\_$number$\_$unique$)$;