Question: where do most immigrants to the u.s. come from (which country )
[{'answer': 'Mexico', 'provenance': [{'wikipedia_id': '15051', 'title': 'Immigration to the United States', 'start_paragraph_id': 19, 'start_character': 392, 'end_paragraph_id': 19, 'end_character': 398, 'bleu_score': 1.0, 'section': 'Section::::History.:20th Century.\n'}]}]