Which of the following code snippets are most likely to perform sign$-$extension on the data $($assume $16$ bit integers and $32$ bit longs$)?$

unsigned int $x=1$;$x++$;

int $y=1$; long $x=-2$;$y=x$;

long $y=1$; int $x=-2$;$y=x$;

char $*$msg $=$ "don't pick me$."$