Question: who played sibella in kind hearts and coronets
[{'answer': 'Joan Greenwood', 'provenance': [{'wikipedia_id': '350908', 'title': 'Kind Hearts and Coronets', 'start_paragraph_id': 1, 'start_character': 88, 'end_paragraph_id': 1, 'end_character': 102, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '350908', 'title': 'Kind Hearts and Coronets', 'start_paragraph_id': 17, 'start_character': 0, 'end_paragraph_id': 17, 'end_character': 37, 'bleu_score': 0.5081327481546141, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1343326149281863066}, 'section': 'Section::::Cast.\n'}]}]