Question: what is a curved linear chain of volcanoes above a subduction zone called
[{'answer': 'A volcanic arc', 'provenance': [{'wikipedia_id': '1102339', 'title': 'Volcanic arc', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1102339', 'title': 'Volcanic arc', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 725, 'bleu_score': 0.886783876899019, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18052634150521248324}, 'section': 'Section::::Abstract.'}]}]