Final answer:
Double-clicking on a geographic field in Tableau's dimensions list automatically adds a map visualization to the workspace, providing an immediate geographical representation of the data. The correct answer is option b.
Step-by-step explanation:
When you double-click on an item that has a geographic role in the dimensions list using Tableau, it is automatically added as a map to the workspace. Tableau recognizes the geographic data and helps you create a visual representation on a map, enabling you to analyze data with a geographical context easily.