Question: who plays sarah walker in brothers and sisters
[{'answer': 'Rachel Griffiths', 'provenance': [{'wikipedia_id': '10238594', 'title': 'Sarah Walker (Brothers & Sisters)', 'start_paragraph_id': 1, 'start_character': 149, 'end_paragraph_id': 1, 'end_character': 165, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '10238594', 'title': 'Sarah Walker (Brothers & Sisters)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 165, 'bleu_score': 0.9181891462193901, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5299017822696418053}, 'section': 'Section::::Abstract.'}]}]