Question: who was the 31st president of the united states
[{'answer': 'Herbert Clark Hoover', 'provenance': [{'wikipedia_id': '13682', 'title': 'Herbert Hoover', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]