Question: who sang unchained melody in the righteous brothers
[{'answer': 'Bobby Hatfield', 'provenance': [{'wikipedia_id': '359664', 'title': 'Unchained Melody', 'start_paragraph_id': 3, 'start_character': 97, 'end_paragraph_id': 3, 'end_character': 111, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '359664', 'title': 'Unchained Melody', 'start_paragraph_id': 12, 'start_character': 0, 'end_paragraph_id': 12, 'end_character': 434, 'bleu_score': 0.9735040436119741, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7609052402474162359}, 'section': 'Section::::The Righteous Brothers versions.\n'}]}]