Question: who headed the freedmen's bureau following the civil war
[{'answer': 'Oliver O. Howard', 'provenance': [{'wikipedia_id': '395175', 'title': "Freedmen's Bureau", 'start_paragraph_id': 2, 'start_character': 497, 'end_paragraph_id': 2, 'end_character': 513, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '395175', 'title': "Freedmen's Bureau", 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 880, 'bleu_score': 0.9566091336550111, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17877456934700447795}, 'section': 'Section::::Abstract.'}]}]