Question: who sang for maria in west side story
[{'answer': 'Marni Nixon', 'provenance': [{'wikipedia_id': '477971', 'title': 'Marni Nixon', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 11, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '477971', 'title': 'Marni Nixon', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 411, 'bleu_score': 0.588929258393258, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 328067308482842772}, 'section': 'Section::::Abstract.'}]}]