Given the functions below:

int fun$1($int n$)\{$

if $($n $<=1)$

return n;

return

$2*$fun$1($n$-1)$;

$\}$

int fun$2($int n$)\{$

if $($n $<=1)$

return n;

return

fun$2($n$-1)+$ fun$2($n$-1)$;

$\}$

The complexity of the functions, fun$1$ and fun$2,$ are respectively described by

A$)$ O$(2^$n$),$ O$(2^$n$)$

B$)$ O$($n$),$ O$(2^$n$)$

C$)$ O$(2^$n$),$ O$($n$)$

D$)$ O$($n$),$ O$($n$)$

E$)$ None of the above