Question: who defeated king darius at the battle of marathon
[{'answer': 'Miltiades , the Athenian general', 'provenance': [{'wikipedia_id': '4806', 'title': 'Battle of Marathon', 'start_paragraph_id': 20, 'start_character': 214, 'end_paragraph_id': 20, 'end_character': 250, 'bleu_score': 1.0, 'section': 'Section::::Prelude.\n'}]}, {'provenance': [{'wikipedia_id': '4806', 'title': 'Battle of Marathon', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 965, 'bleu_score': 0.9700126434602441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10869197748329266437}, 'section': 'Section::::Abstract.'}]}]