Question: where is north america's largest oil field
[{'answer': 'Mexico', 'provenance': [{'wikipedia_id': '219949', 'title': 'List of oil fields', 'start_paragraph_id': 2, 'start_character': 321, 'end_paragraph_id': 2, 'end_character': 327, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]