what will be the value of $a?

Given the following code, what will be the value of $a?
<code>
$a = array(‘a’, ‘b’);
array_push($a, array(1, 2));
</code>

A.
array(‘a’, ‘b’, 1, 2)

B.
array(1, 2, ‘a’, ‘b’)

C.
array(array(1, 2), ‘a’, ‘b’)

D.
None of the above