Question: on auscultation the heart sound s1 indicates the closure of the
[{'answer': 'atrioventricular valves', 'provenance': [{'wikipedia_id': '237412', 'title': 'Heart sounds', 'start_paragraph_id': 3, 'start_character': 31, 'end_paragraph_id': 3, 'end_character': 54, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]