Question: which emperor started the second persian invasion of greece
[{'answer': 'King Xerxes I', 'provenance': [{'wikipedia_id': '20198436', 'title': 'Second Persian invasion of Greece', 'start_paragraph_id': 1, 'start_character': 94, 'end_paragraph_id': 1, 'end_character': 107, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '20198436', 'title': 'Second Persian invasion of Greece', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 638, 'bleu_score': 0.9180971937247071, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15944846266475595950}, 'section': 'Section::::Abstract.'}]}]