What does the following recursive method do, if called from another public method, where the parameter p is reference to the tree root?

private int undefined_Method(Node p)

{

if ( p == null ) return 0;

if ( p.left == null || p.right == null )

return p.data;

if (p.left != null && p.right = null)

return p.data + undefined_Method(p.left) + undefined_Method(p.right);

else return undefined_Method(p.left) + undefined_Method(p.right);

}

	a.	It returns the summation of data of the leaf nodes and nodes having only right child.
	b.	It returns the summation of the data of all the nodes.
	c.	It returns the summation of data of the leaf nodes and nodes having only left child.
	d.	It returns the summation of data of leaf nodes and nodes having two child nodes.