Which tool would be most appropriate for refining a selection edge in photo editing?

The most appropriate tool for refining a selection edge in photo editing is the Feather tool. This tool allows you to create a soft transition at the edges of a selection, which can help blend the selected area with the surrounding pixels more seamlessly. By applying a feathering effect, you can reduce the harshness of the edge, making it less noticeable and achieving a more polished and natural look.

In contrast, the other tools serve different purposes. The Eraser is designed to remove pixels and is not focused on refining the edges of selections but rather on deleting content entirely. The Brush tool is meant for painting and adding details, which does not specifically address edge refinement. The Clone Stamp is typically used to replicate part of an image, helping with corrections or removing unwanted elements, but it does not refine selection edges. Thus, the Feather tool stands out as the best choice for enhancing the quality of selections in photo editing.