What does this recursive method do$?$

private int Count$($Node node$)$

$\{$

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

return $0$ ;

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

return $1$ ;

else

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

$\}$

count number of nodes in the binary tree

count number of leaf nodes in the binary tree

count number of nodes that has one child in the binary tree

count number of nodes that has two children in the binary tree