Question: which of the three west african kingdoms was the largest
[{'answer': 'The Oyo Empire', 'provenance': [{'wikipedia_id': '14762552', 'title': 'African empires', 'start_paragraph_id': 17, 'start_character': 12, 'end_paragraph_id': 17, 'end_character': 26, 'bleu_score': 1.0, 'section': 'Section::::Empires of 15th–19th century Africa.:West Africa.\n'}]}, {'provenance': [{'wikipedia_id': '14762552', 'title': 'African empires', 'start_paragraph_id': 17, 'start_character': 0, 'end_paragraph_id': 17, 'end_character': 575, 'bleu_score': 0.9456135312474161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14774325453727993014}, 'section': 'Section::::Empires of 15th–19th century Africa.:West Africa.\n'}]}]