Question: tornadoes commonly occur in which of the following regions of the united states
[{'answer': 'The Great Plains', 'provenance': [{'wikipedia_id': '18436515', 'title': 'Tornadoes in the United States', 'start_paragraph_id': 2, 'start_character': 71, 'end_paragraph_id': 2, 'end_character': 87, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'the Midwest', 'provenance': [{'wikipedia_id': '18436515', 'title': 'Tornadoes in the United States', 'start_paragraph_id': 2, 'start_character': 89, 'end_paragraph_id': 2, 'end_character': 100, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'the Mississippi Valley', 'provenance': [{'wikipedia_id': '18436515', 'title': 'Tornadoes in the United States', 'start_paragraph_id': 2, 'start_character': 102, 'end_paragraph_id': 2, 'end_character': 124, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'the southern United States', 'provenance': [{'wikipedia_id': '18436515', 'title': 'Tornadoes in the United States', 'start_paragraph_id': 2, 'start_character': 129, 'end_paragraph_id': 2, 'end_character': 155, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '18436515', 'title': 'Tornadoes in the United States', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 879, 'bleu_score': 0.967405819735595, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13096362328332423076}, 'section': 'Section::::Abstract.'}]}]