Question: when was the first drive in movie theater opened
[{'answer': '1921', 'provenance': [{'wikipedia_id': '310594', 'title': 'Drive-in theater', 'start_paragraph_id': 7, 'start_character': 3, 'end_paragraph_id': 7, 'end_character': 7, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '310594', 'title': 'Drive-in theater', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 391, 'bleu_score': 0.9684940092844061, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14020125294732246306}, 'section': 'Section::::History.\n'}]}]