What is the output of the following code? <code> $a = ‘a’; $b = ‘b’; e

What is the output of the following code?
<code>
$a = ‘a’; $b = ‘b’;
echo isset($c) ? $a.$b.$c : ($c = ‘c’).’d’;
</code>

A.
abc

B.
cd

C.
0d