Question: what type of muscle is in the iris
[{'answer': 'sphincter', 'provenance': [{'wikipedia_id': '2939684', 'title': 'Iris sphincter muscle', 'start_paragraph_id': 0, 'start_character': 5, 'end_paragraph_id': 0, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2939684', 'title': 'Iris sphincter muscle', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 258, 'bleu_score': 0.953991849837532, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16388684918283054425}, 'section': 'Section::::Abstract.'}]}]