Consider the following C$-$function:

double foo $($int n$)$

$\{$

int i;

double sum;

if $($n $==0)$ return $1\mathrm{.}0$;

else

$\{$

sum $=0\mathrm{.}0$;

for $($i $=0$; i $<$ n; i$++)$

sum $+=$ foo $($i$)$;

return sum;

$\}$

$\}$

The space complexity of the above function is:

Question $4$ options:

O$($nn$)$

O$($n$!)$

O$(1)$

O$($n$)$