Question: who won christina grimmie's season of the voice
[{'answer': 'Josh Kaufman', 'provenance': [{'wikipedia_id': '39405808', 'title': 'The Voice (American season 6)', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 12, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]