Question: where is the largest megalopolis in the us located
[{'answer': 'Great Lakes', 'provenance': [{'wikipedia_id': '5688834', 'title': 'Megalopolis', 'start_paragraph_id': 20, 'start_character': 165, 'end_paragraph_id': 20, 'end_character': 176, 'bleu_score': 1.0, 'section': 'Section::::North America.:United States.\n'}]}]