What is true about the table includes?

CREATE TABLE includes

$($ productid CHAR$(3)$ NOT NULL,

tid VARCHAR$(8)$ NOT NULL,

quantity INT NOT NULL,

PRIMARY KEY $($productid$,$ tid$),$

FOREIGN KEY $($productid$)$ REFERENCES product$($productid$),$

FOREIGN KEY $($tid$)$ REFERENCES salestransaction$($tid$))$;

The table includes columns which are optional

All of the column datatypes are character

The table has a composite primary key

Rows are uniquely identified by productid