Let F : $\{0,1\}$

n $\backslash$times $\{0,1\}$

n $->\{0,1\}$

n pseudorandom function. Check them out below

functions in terms of their pseudorandomness:

$1.$ F$1($k$,$ x$)=$ F$($k$,$ x$)||0$

$2.$ F$2($k$,$ x$)=$ F$($k$,$ x$)$ x

$3.$ F$3($k$,$ x$)=$ F$($k$,$ x $1$

n

$)$

$4.$ F$4($k$,$ x$)=$ F$($k$,$ x$)||$F$($k$,$ F$($k$,$ x$))$