Question: the polar caps on mars are most probably made up of
[{'answer': 'water ice', 'provenance': [{'wikipedia_id': '28203358', 'title': 'Martian polar ice caps', 'start_paragraph_id': 2, 'start_character': 44, 'end_paragraph_id': 2, 'end_character': 53, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '28203358', 'title': 'Martian polar ice caps', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 924, 'bleu_score': 0.988200073497952, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2856361162829287380}, 'section': 'Section::::Abstract.'}]}]