Which statement about data marts and data warehouses is accurate?

• A. Data marts and data warehouses are the same
• B. A data mart is a small-scale version of a data warehouse
• C. A data warehouse is a subset of a data mart
• D. Data marts are used only for testing

Answer: (B)

Data marts are smaller, focused data stores designed for a specific department or business process. They contain a subset of the data found in a data warehouse (or are built directly from source systems) to meet the needs of a particular user group. This focused scope makes them quicker to implement and easier to query for that group, while a data warehouse serves as the central, integrated repository for organization-wide analytics.

So the statement that a data mart is a small-scale version of a data warehouse best captures the relationship: it emphasizes both the smaller size and the targeted purpose. The other ideas—that they are the same, that a warehouse is a subset of a data mart, or that data marts exist only for testing—don’t align with how these structures are typically used in practice.