What is the logical error in the findFun method?

int findFun $($Node node$)\{$

if $($node$.$key $==$ null$)$

return $0$ ;

else

$\{$

int length $=1$;

length $+=$ findFun $($node: node.left$)$;

length $+=$ findFun $($node: node.right$)$;

return length;

A$.$ The method counts all nodes instead of finding the maximum.

B$.$ The method doesn't count the root node when finding the maximum.

C$.$ The method doesn't count the leaf nodes when finding the maximum.

D$.$ The method returns $0$ instead of $-1$ for empty tree.