Question: who won us open women's singles 2017
[{'answer': 'Sloane Stephens', 'provenance': [{'wikipedia_id': '54683068', 'title': "2017 US Open – Women's Singles", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 15, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '54683068', 'title': "2017 US Open – Women's Singles", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 413, 'bleu_score': 0.806458095317608, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4882581601719291263}, 'section': 'Section::::Abstract.'}]}]