Question: when was the twin towers built in new york city
[{'answer': '1973', 'provenance': [{'wikipedia_id': '45645094', 'title': 'World Trade Center (1973–2001)', 'start_paragraph_id': 0, 'start_character': 20, 'end_paragraph_id': 0, 'end_character': 24, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '45645094', 'title': 'World Trade Center (1973–2001)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 574, 'bleu_score': 0.653525605682383, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8615086599696514814}, 'section': 'Section::::Abstract.'}]}]