Question: who won last triple crown of horse racing
[{'answer': 'Justify', 'provenance': [{'wikipedia_id': '19116721', 'title': 'Triple Crown of Thoroughbred Racing (United States)', 'start_paragraph_id': 3, 'start_character': 303, 'end_paragraph_id': 3, 'end_character': 310, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]