Question: who played clair huxtable's parents on the cosby show
[{'answer': 'Ethel Ayler', 'provenance': [{'wikipedia_id': '11567670', 'title': 'List of The Cosby Show characters', 'start_paragraph_id': 82, 'start_character': 28, 'end_paragraph_id': 82, 'end_character': 39, 'bleu_score': 1.0, 'section': 'Section::::Recurring characters.\n'}]}, {'answer': 'Joe Williams', 'provenance': [{'wikipedia_id': '11567670', 'title': 'List of The Cosby Show characters', 'start_paragraph_id': 89, 'start_character': 24, 'end_paragraph_id': 89, 'end_character': 36, 'bleu_score': 1.0, 'section': 'Section::::Recurring characters.\n'}]}]