Question: how many u-boats did germany have in world war 2
[{'answer': 'some 1,250 U-boats', 'provenance': [{'wikipedia_id': '509836', 'title': 'List of German U-boats', 'start_paragraph_id': 311, 'start_character': 46, 'end_paragraph_id': 311, 'end_character': 64, 'bleu_score': 1.0, 'section': 'Section::::World War II U-boats.\n'}]}, {'provenance': [{'wikipedia_id': '509836', 'title': 'List of German U-boats', 'start_paragraph_id': 311, 'start_character': 0, 'end_paragraph_id': 311, 'end_character': 87, 'bleu_score': 0.673904706256473, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1891755768505464331}, 'section': 'Section::::World War II U-boats.\n'}]}]