Answer:
Variable Where Declared
In Sub1 :
A Sub1
Y Sub1
Z Sub1
X Main
In Sub2:
A Sub2
B Sub2
Z Sub2
Y Sub1
X Main
In Sub3 :
A Sub3
X Sub3
W Sub3
Y Main
Z Main
Explanation:
In static-scoped languages with nested subprograms, the declaration of a variable is checked with the subprogram, if it is not found, it check within the parent method that called it, it continue until it find a declaration, if no declaration is found, it display an error.
In Sub1, a, y, z is declared there while the declaration of x is found in main.
In Sub2, a, b, z is declared, declaration of y is found in sub1 and declaration of x is found in main.
In Sub3, a, x, w is declared while the declaration of y, z is from the main.
