Question: who won the men's single title in french open tennis tournament 2015
[{'answer': 'Stan Wawrinka', 'provenance': [{'wikipedia_id': '45688553', 'title': "2015 French Open – Men's Singles", 'start_paragraph_id': 3, 'start_character': 13, 'end_paragraph_id': 3, 'end_character': 26, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]