With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Philip V of Spain had two reigns.
text_B: The Marian Conspiracy is a Big Finish Productions audio drama based on the long-running British science fiction television series '' Doctor Who .. Big Finish Productions. Big Finish Productions. Doctor Who. Doctor Who. audio drama. List of Doctor Who audio plays by Big Finish. science fiction television. science fiction on television
not_related.