With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Pembroke Castle is the largest castle in Wales that is privately owned.
text_B: The Armstrong Whitworth A.W. 14 Starling was a British single-engine biplane fighter developed for the Royal Air Force in the 1920s .. British. United Kingdom. biplane. biplane. fighter. fighter aircraft. Royal Air Force. Royal Air Force. It was unsuccessful , with the Bristol Bulldog being selected instead .. Bristol Bulldog. Bristol Bulldog
not_related.