Question: when did grand canyon become a national park
[{'answer': 'February 26 , 1919', 'provenance': [{'wikipedia_id': '46989', 'title': 'Grand Canyon', 'start_paragraph_id': 46, 'start_character': 986, 'end_paragraph_id': 46, 'end_character': 1004, 'bleu_score': 1.0, 'section': 'Section::::History.:European arrival and settlement.:Federal protection: National Monument and Park.\n'}]}, {'provenance': [{'wikipedia_id': '46989', 'title': 'Grand Canyon', 'start_paragraph_id': 46, 'start_character': 0, 'end_paragraph_id': 46, 'end_character': 1003, 'bleu_score': 0.9872197907830691, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13886870427561524544}, 'section': 'Section::::History.:European arrival and settlement.:Federal protection: National Monument and Park.\n'}]}]