1. Consider the following JavaScript-like program: var X, Y, Z; function subi () { var a, Y, Z; function sub2() { var a, b, Z; } } function var sub3() { a, X, W; } List all the variables, along with the program units where they are declared, that are visible in the bodies of sub1, sub2, and sub3, assuming dynamic scoping is used. Assume the calling sequence is sub30) -> sub1() -> sub20). (10 points)