Consider the following program.

program main

int $x,y$;

proc A;

int $z$;

proc B;

call $C$; print $x$;$x$:$=x+1$; end $B$

proc C;

int $x,z$;

; call $D$; print $x$; end $C$

call $B$; print $x$; end $A$

proc D;

int $x$;

proc E;

int $y,z$;

proc $F$;

end $F$

call F; print $x$;$x$:$=x+1$; end $E)$

call E; print $x$; end $D$

call $A$; print $x$; $($end main$)$

$($a$)$ List the referencing environment $($visible variables$)$ in proc $C$ if static scoping is used.

$($b$)$ List the referencing environment $($visible variables$)$ in proc D if dynamic scoping is

used.

Note: main calls A calls B calls C calls D calls E calls F$.$

$($c$)$ List the units that can be called by proc E if static scoping is used.

$($d$)$ Give the program output if static scoping is used.

$($e$)$ Give the program output if dynamic scoping is used.