Question: when did rationing start in britain during world war 2
[{'answer': '1940', 'provenance': [{'wikipedia_id': '1279880', 'title': 'Rationing in the United Kingdom', 'start_paragraph_id': 10, 'start_character': 112, 'end_paragraph_id': 10, 'end_character': 116, 'bleu_score': 1.0, 'section': 'Section::::Second World War.\n'}]}, {'provenance': [{'wikipedia_id': '1279880', 'title': 'Rationing in the United Kingdom', 'start_paragraph_id': 10, 'start_character': 9, 'end_paragraph_id': 10, 'end_character': 726, 'bleu_score': 0.78050807776953, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3188280923529972668}, 'section': 'Section::::Second World War.\n'}]}]