Question: who ruled the largest empire in world history
[{'answer': 'British Empire', 'provenance': [{'wikipedia_id': '3550538', 'title': 'List of largest empires', 'start_paragraph_id': 5, 'start_character': 141, 'end_paragraph_id': 5, 'end_character': 155, 'bleu_score': 1.0, 'section': 'Section::::Largest empires by land area.:Empires at their greatest extent.\n'}]}]