What is the output of the following code?
class a
{
public $val;
function renderVal (a $a)
{
if ($a) {
echo $a->val;
renderVal (null);
A . A syntax error in the function declaration line
B . An error, because null is not an instance of ‘a’
C . Nothing, because a null value is being passed to renderVal()
D . NULL
Answer: B