What does this recursive method do$?$

private int method$($Node node$)$

$\{$

if $($node $==$ null $)$

return $0$;

else if$(($node$.$left $!=$ null && node.right $==$ null$))$

return $(1+$ method$($node$.$left$))$;

else

return $($method$($node$.$left$)+$ method$($node$.$right$))$;

$\}$

count the number of nodes with the left child only

count the number of nodes with the one child only

count the number of nodes

count the number of nodes with the right child only