What purpose do adjustment layers serve in Photoshop?

Adjustment layers in Photoshop are specifically designed to facilitate color and tonal adjustments without permanently affecting the original image. This non-destructive methodology is crucial for maintaining flexibility during the editing process, as it allows for changes to be made and refined at any point without committing to the alterations on the base layer.

When you create an adjustment layer, you can apply various effects—such as brightness, contrast, hue/saturation, and others—while keeping the underlying image intact. This means that if you decide to adjust the brightness later or even revert back to the original colors, you can do so easily by modifying the adjustment layer rather than starting over on the original image.

The other choices deal with different functionalities in Photoshop. The option describing effects that permanently alter the original image does not align with the non-destructive nature of adjustment layers. Enhancing texture pertains to another aspect of image editing and is not directly related to color and tonal adjustments. Merging multiple images involves layer management and compositing, which is a different function than what adjustment layers are designed to do. Hence, the role of adjustment layers in enabling non-destructive color and tonal changes is accurately captured in the correct answer.