Trace the following program segment and assume that no errors or cascading termination occur.

$$

#include

#include

#include

int main$()\{$

$$ pid$\_$t x $=0,$ y $=0$;

$$ x $=$ fork$()$;

$$ if $($x $==0)\{$

$$ x $=$ fork$()$;

$$ if $($x $==0)\{$

$$ printf$("$x $=\%$d$,$ y $=\%$d

$",$ x$,$ y$)$;

$\}$

$$ printf$("$x $=\%$d$,$ y $=\%$d

$",$ x$,$ y$)$;

$\}$

$$ printf$("$x $=\%$d$,$ y $=\%$d

$",$ x$,$ y$)$;

$$ if $($x $==0$ && y $==0)\{$

$$ printf$("$x $=\%$d$,$ y $=\%$d

$",$ x$,$ y$)$;

$\}$

$$ return $0$;

$\}$

$$

A$.$ How many lines are printed out by this program?

B$.$ In how many of these printed lines is the value of x $0?$

C$.$ In how many of these printed lines is the value of y $0?$