9. Consider the following program procedure Main is X, Y, Integer; procedure Subl is A, Y, Z Integer; beginof Subl end; -of Sub1 A, x, Integer; procedure Sub2 is procedure Sub3 is A, B, Z Integer; beginof Sub3 end; of Sub3 beginof Sub2 end;-of Sub2 begin of Main end;--of Main List all the variables, along with the program units where they are declared, that are visible in the bodies of Sub1, Sub2, and Sub3, assum- ing static scoping is used