Question: what type of warfare was going on in the battle of britain
[{'answer': 'air', 'provenance': [{'wikipedia_id': '57974', 'title': 'Battle of Britain', 'start_paragraph_id': 1, 'start_character': 228, 'end_paragraph_id': 1, 'end_character': 231, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '57974', 'title': 'Battle of Britain', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 567, 'bleu_score': 0.744920216667727, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3914792123046975686}, 'section': 'Section::::Abstract.'}]}]