Question: who plays dr. riggs on grey's anatomy
[{'answer': 'Martin Henderson', 'provenance': [{'wikipedia_id': '2251860', 'title': 'Martin Henderson', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 16, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2251860', 'title': 'Martin Henderson', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 395, 'bleu_score': 0.7449901145337501, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5786793376216463710}, 'section': 'Section::::Abstract.'}]}]