Question: what type of warfare was used in wwi
[{'answer': 'Trench warfare', 'provenance': [{'wikipedia_id': '182259', 'title': 'Trench warfare', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '182259', 'title': 'Trench warfare', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 395, 'bleu_score': 0.8194774539983901, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6769612476496928597}, 'section': 'Section::::Abstract.'}]}]