A database stores the data of the sales using the primary key RECEIVE$\_$NUM in the SALE table and the products in the PRODUCT table with primary key PROD$\_$NUM. To create the relation that represents what products were sold in a SALE a M:N relationship is necessary. What should be used to represent this in a relational model?

composite attribute with RECEIVE$\_$NUM $+$ PROD$\_$NUM

composite entity with RECEIVE$\_$NUM $+$ PROD$\_$NUM

a product table SALE x PRODUCT

a join table S$LE $+$ PRODUCT