What feature should you use in combination with an adjustment layer to isolate the affected image area non-destructively?

To isolate the affected image area non-destructively while using an adjustment layer, employing a layer mask is the ideal approach. A layer mask allows you to control the visibility of different parts of the adjustment layer, effectively enabling you to "paint" the effects of the adjustment in or out of specific areas of your image without permanently altering the original layer beneath.

When applying adjustments to a photo, it's common to want those changes to affect only certain areas rather than the entire image. By using a layer mask, you can paint with black to hide the adjustment effect in areas where you don’t want it and paint with white to reveal it where you do want the adjustment to be visible. This selective application ensures that you maintain the ability to edit the mask later, thereby preserving the integrity of your original image and allowing for more flexibility in your workflow.

In contrast, while clipping masks and smart objects serve useful functions, they do not specifically enable selective adjustments in the way layer masks do. A clipping mask restricts an adjustment layer to the contents of a specific layer beneath it, while smart objects allow for non-destructive editing of layered content, but they don’t by themselves isolate image areas for targeted adjustment applications. Paths are mainly used for creating vector shapes and selections