$3.$ What does the following statement do:

ALTER TABLE DEPT$\_$TEST

ADD CONSTRAINT unq$\_$dept$\_$det UNIQUE $($DEPT$\_$ID$,$ DEPARTMENT$\_$NAME$)$ ;

It alters the DEPT$\_$TEST table to add a composite primary key comprising of the DEPT$\_$ID and DEPARTMENT$\_$NAME.

It alters the DEPT$\_$TEST table to add a composite unique key comprising of the DEPT$\_$ID and DEPARTMENT$\_$NAME.

It alters the DEPT$\_$TEST table to add a composite foreign key comprising of the DEPT$\_$ID and DEPARTMENT$\_$NAME.

It alters the DEPT$\_$TEST table to add a the DEPT$\_$ID and DEPARTMENT$\_$NAME columns.