Question: who is the chief operating officer of facebook
[{'answer': 'Sheryl Kara Sandberg', 'provenance': [{'wikipedia_id': '1624080', 'title': 'Sheryl Sandberg', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1624080', 'title': 'Sheryl Sandberg', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 622, 'bleu_score': 0.891143342563885, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13791304056614186951}, 'section': 'Section::::Abstract.'}]}]