Question: who has won the us open golf title 2018
[{'answer': 'Defending champion Brooks Koepka', 'provenance': [{'wikipedia_id': '54368265', 'title': '2018 U.S. Open (golf)', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 32, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '54368265', 'title': '2018 U.S. Open (golf)', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 343, 'bleu_score': 0.96746874041754, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13003669236861807936}, 'section': 'Section::::Abstract.'}]}]