What could a workbook contain that directly affects its functionality?

A workbook can include reference worksheets from other resources, which directly impacts its functionality. When a workbook has reference worksheets, it allows for data integration and enhanced analysis capabilities. These reference worksheets can provide additional data points or variables, making it easier to create comprehensive reports and models that draw on a broader context. By incorporating data from other resources, users can develop more sophisticated analytics and visualizations.

Using reference worksheets allows for the ability to cross-reference data, perform comparisons, or simulate scenarios based on external data inputs. This enriches the workbook's functionality and agility in responding to varied analytical needs.

Other options represent factors that could hinder the workbook's performance rather than enhancing it. Non-compatible file formats can lead to data incompatibility issues, making it difficult to open or use the workbook correctly. Outdated formulas and calculations can produce inaccurate results, compromising any insights derived from the data. Unlinked data sources can result in inefficiencies since they require manual updates and lack real-time data integration, making the workflow sluggish and error-prone.