Question: what is currently the largest crop in the usa
[{'answer': 'Corn', 'provenance': [{'wikipedia_id': '242778', 'title': 'Agriculture in the United States', 'start_paragraph_id': 1, 'start_character': 539, 'end_paragraph_id': 1, 'end_character': 543, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]