Question: who led the work of the freedmen's bureau
[{'answer': 'Oliver Otis Howard', 'provenance': [{'wikipedia_id': '395175', 'title': "Freedmen's Bureau", 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 18, 'bleu_score': 1.0, 'section': 'Section::::Achievements.:Education.\n'}]}, {'provenance': [{'wikipedia_id': '395175', 'title': "Freedmen's Bureau", 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 549, 'bleu_score': 0.919888885234014, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8618174732898947264}, 'section': 'Section::::Achievements.:Education.\n'}]}]