An analyst has a filled map of council areas shaded by recycling rate and wants to add a second mark layer showing depot locations as points on the same map. They open the Marks card menu but find no option to add a layer. The view currently builds its map from a single pair of generated coordinate fields on Rows and Columns. What must be present for the Add Mark Layer option to become available?
- AA second geographic field dragged onto the map pane so Tableau can place it as a new layer Correct
- BA dual-axis configuration applied to the two generated latitude fields on the Rows shelf
- CA blend between two separate data sources joined on a common region key
- DA conversion of the recycling-rate measure into a discrete dimension first
Why A is correct: Dropping another geographic field onto the map canvas creates an additional mark layer, which is the action that exposes and uses the layering capability.
Why B is wrong: Dual axis with two latitude pills is the older technique for overlaying marks, but it is not what enables the modern Add Mark Layer option, which works by dropping a geographic field onto the canvas.
Why C is wrong: Data blending is unrelated to map layering, so configuring a blend would not produce the Add Mark Layer option for points on the same map.
Why D is wrong: Changing the measure to discrete affects how the existing layer is shaded, not whether a new mark layer can be added, so it does not solve the problem.