With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Christopher Columbus sailed across a lake.
text_B: Oskorusa is a hill close to the city of Smederevska Palanka , Serbia .. Smederevska Palanka. Smederevska Palanka. Serbia. Serbia. The top of the hill is 265 m above sea level .
not_related.