In a data model where a single product can appear in many sales records, which cardinality describes the relationship between the product and sales tables?

• A. One-to-one
• B. One-to-many
• C. Many-to-many
• D. None

Answer: (D)

The key idea is a one-to-many relationship. A single product can appear in many sales records, while each individual sales record references only one product. This is typically modeled with a foreign key in the sales table that points to the product.

If a product were related to at most one sale, that would be one-to-one, which isn’t the case here. If a sale could include multiple products and a product could appear in many sales, that would be many-to-many and usually requires a junction or line-item table to model the multiple associations. None isn’t appropriate because there is an actual relationship between the two tables.