Question: who played christina yang on grey's anatomy
[{'answer': 'Sandra Miju Oh', 'provenance': [{'wikipedia_id': '363002', 'title': 'Sandra Oh', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]