Question: who sings lead vocals on while my guitar gently weeps
[{'answer': 'George Harrison', 'provenance': [{'wikipedia_id': '921672', 'title': 'While My Guitar Gently Weeps', 'start_paragraph_id': 1, 'start_character': 174, 'end_paragraph_id': 1, 'end_character': 189, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]