Assume you are implementing a database from the preceding diagram. Which of these is the best way to implement the relationship identified by the number 3?
a. Post the primary key of customers in sales as a foreign key.
b. Post the primary key of sales in customers as a foreign key.
c. Create a linking table between sales and customers.
d. All of these are acceptable.
e. None of these are acceptable.

Inventory Cash 1..* 1..1 5 6 O..* O..* Sales 7 ?..? ?..? Cash Receipts 0..* O..* 3 O..* O..* 1 1..1 2 1..1 4 1..1 Employees Customers 1..1