What ArcGIS Online analysis tool should be used to combine areas that share a common edge?

The appropriate tool to combine areas that share a common edge in ArcGIS Online is the Dissolve Boundaries tool. This tool functions by taking a feature layer and merging adjacent features that have the same attribute value, which effectively creates a single, cohesive feature. This is particularly useful for simplifying datasets, such as consolidating administrative boundaries or land use areas, while maintaining the integrity of underlying data attributes.

While other tools mentioned in the options have their specific uses, they do not serve the same purpose as Dissolve Boundaries. For instance, Extract Data is designed for retrieving a portion of a dataset based on specific criteria, while Overlay Layers is utilized for performing spatial analysis by layering different datasets to understand their relationships. Merge Layers, on the other hand, is intended for combining multiple layers into a single layer but does not merge adjacent boundaries based on shared edges effectively. Therefore, the Dissolve Boundaries tool stands out for its specific capability to enhance the spatial representation of features with common edges.