Question: iodine is added to salt in the united states to prevent which deficiency
[{'answer': 'iodine deficiency', 'provenance': [{'wikipedia_id': '1232890', 'title': 'Iodised salt', 'start_paragraph_id': 1, 'start_character': 155, 'end_paragraph_id': 1, 'end_character': 172, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1232890', 'title': 'Iodised salt', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 567, 'bleu_score': 0.976327165973018, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17830108767555251091}, 'section': 'Section::::Abstract.'}]}]