1. Consider the following JavaScript-like program: var X, Y, subi() { function var a, b, z; z; function var a, y, z; sub2 () { } sub3() { function var a, X, W; } List all the variables, along with the program units where they are declared, that are visible in the bodies of subl, sub2, and sub3, assuming dynamic scoping is used. Assume the calling sequence is sub30) -> sub10) -> sub20. (10 points)