Question: what tsar was overthrown in the russian revolution
[{'answer': 'Emperor Nicholas II', 'provenance': [{'wikipedia_id': '25762', 'title': 'Russian Revolution', 'start_paragraph_id': 2, 'start_character': 611, 'end_paragraph_id': 2, 'end_character': 630, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]