Question: who won the 2018 us open womens singles
[{'answer': 'Naomi Osaka', 'provenance': [{'wikipedia_id': '58448505', 'title': "2018 US Open – Women's Singles final", 'start_paragraph_id': 1, 'start_character': 173, 'end_paragraph_id': 1, 'end_character': 184, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]