Which tool allows you to select Sample All Layers and modify the brush size?

The right choice for selecting "Sample All Layers" and modifying the brush size is the brush tool. This tool is specifically designed for painting and allows users to work with different brush sizes according to their needs. The option to select "Sample All Layers" is particularly useful when working in a situation where adjustments need to be made to a composite image but the active layer doesn’t contain the colors or effects that the user wants to manipulate. This capability enhances the versatility of the brush tool, enabling it to sample from multiple layers rather than being limited to just one.

The other tools listed, like the quick selection tool, magic wand tool, and polygonal lasso tool, serve different functions primarily centered around selection rather than painting. They focus on altering selections based on color ranges or shape outlines, but they do not provide the brush functionality or the option to modify brush size in the way the brush tool does.