Question: who has the most us open tennis titles
[{'answer': 'Richard Sears', 'provenance': [{'wikipedia_id': '858572', 'title': "List of US Open men's singles champions", 'start_paragraph_id': 7, 'start_character': 36, 'end_paragraph_id': 7, 'end_character': 49, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'answer': 'William Larned', 'provenance': [{'wikipedia_id': '858572', 'title': "List of US Open men's singles champions", 'start_paragraph_id': 7, 'start_character': 63, 'end_paragraph_id': 7, 'end_character': 77, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'answer': 'Bill Tilden', 'provenance': [{'wikipedia_id': '858572', 'title': "List of US Open men's singles champions", 'start_paragraph_id': 7, 'start_character': 105, 'end_paragraph_id': 7, 'end_character': 116, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '858572', 'title': "List of US Open men's singles champions", 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 626, 'bleu_score': 0.8521621110233021, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14610730060350055562}, 'section': 'Section::::History.\n'}]}]