Question: who was the chairman of the constituent assembly when our constitution was enacted
[{'answer': 'B.R. Ambedkar'}, {'provenance': [{'wikipedia_id': '315776', 'title': 'Constitution of India', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 455, 'bleu_score': 0.8589458143212211, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11155775969642387853}, 'section': 'Section::::Abstract.'}]}]