Postal stamp on Asoka

The Union minister Mr. Ravi Shankar Prasad has recently released a postal stamp on which of the following Maurya Kings?
[A]Chandragupta Maurya
[D]None of them

The Union Telecom Minister Mr. Ravi Shankar Prasad released a Rs.5 postal stamp in honour of Ashoka, the Great, the great Indian emperor of Mauryan dynasty.