Polygon Grid Labeling

Morning All, I have 4 equal polygons next to each other and i need to label them A,B C,B. Im struggling with my lists. They currently have no attributes My approach is to create a center point for all of them, to get the x and y. Then A should be the one with the smallest X and smallest Y, then B should be the Largest X and smallest Y etc etc. i get the inside x,y for all then build a list from them then sort the list by inside x but struggle from here. im unsure how to a list by two values ,ie x and y. i have tried list indexer, list exploder.

Thanks Steve point for each polygon then look for the [polygon with the smallest X and Y, this = A, The smallest X and