Question: who won the us womens open in 2013
[{'answer': 'Serena Williams', 'provenance': [{'wikipedia_id': '36705281', 'title': '2013 US Open (tennis)', 'start_paragraph_id': 2, 'start_character': 16, 'end_paragraph_id': 2, 'end_character': 31, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '36705281', 'title': '2013 US Open (tennis)', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 228, 'bleu_score': 0.943604326170661, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5739024279302697584}, 'section': 'Section::::Abstract.'}]}]