Which rocks could be represented by the circles X Y and Z?

Without a specific diagram or context for circles X, Y, and Z, it's difficult to determine the exact types of rocks they represent. However, in general, these could represent different types of rocks such as igneous (X), sedimentary (Y), and metamorphic (Z). Each rock type has distinct characteristics based on its formation processes. If you provide more information or context about the circles, I can give a more tailored response.