Question: who sang lead vocals on sunshine of your love
[{'answer': 'Jack Bruce', 'provenance': [{'wikipedia_id': '1553343', 'title': 'Sunshine of Your Love', 'start_paragraph_id': 1, 'start_character': 204, 'end_paragraph_id': 1, 'end_character': 214, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1553343', 'title': 'Sunshine of Your Love', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 557, 'bleu_score': 0.9244082807420161, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15485864392142498748}, 'section': 'Section::::Abstract.'}]}]