Question: what age horse runs in the kentucky derby
[{'answer': 'three - year - old', 'provenance': [{'wikipedia_id': '17135', 'title': 'Kentucky Derby', 'start_paragraph_id': 9, 'start_character': 453, 'end_paragraph_id': 9, 'end_character': 480, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '17135', 'title': 'Kentucky Derby', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 318, 'bleu_score': 0.690835941605075, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5885164809418216959}, 'section': 'Section::::Abstract.'}]}]