Question: when did the diamondbacks become a baseball team
[{'answer': '1998', 'provenance': [{'wikipedia_id': '2129', 'title': 'Arizona Diamondbacks', 'start_paragraph_id': 3, 'start_character': 339, 'end_paragraph_id': 3, 'end_character': 343, 'bleu_score': 1.0, 'section': 'Section::::Franchise history.\n'}]}]