Question: who has the most nba championships in nba history
[{'answer': 'Bill Russell', 'provenance': [{'wikipedia_id': '10110325', 'title': 'List of NBA players with most championships', 'start_paragraph_id': 2, 'start_character': 22, 'end_paragraph_id': 2, 'end_character': 34, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '10110325', 'title': 'List of NBA players with most championships', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1117, 'bleu_score': 0.8952127513580991, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2508094460853357123}, 'section': 'Section::::Abstract.'}]}]