Consider the following relations for a database that keeps track of automobile sales in a car dealership $($OPTION refers to some optional equipment installed on an automobile$)$:

CAR $($Serial$\_$no$,$ Model, Manufacturer, Price$)$

OPTION $($Serial$\_$no$,$ Option$\_$name, Price$)$

SALE $($Salesperson$\_$id$,$ Serial$\_$no$,$ Date, Sale$\_$price$)$

SALESPERSON $($Salesperson$\_$id$,$ Name, Phone$)$

First, specify the foreign keys for this schema, stating any assumptions you make. Next, populate the relations with a few sample tuples, and then give an example of an insertion in the SALE and SALESPERSON relations that violates the referential integrity constraints and of another insertion that does not.