Question: what unit of measurement is used in mexico
[{'answer': 'The Metric system', 'provenance': [{'wikipedia_id': '45186112', 'title': 'Mexican units of measurement', 'start_paragraph_id': 1, 'start_character': 99, 'end_paragraph_id': 1, 'end_character': 116, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '45186112', 'title': 'Mexican units of measurement', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 175, 'bleu_score': 0.934334813046729, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1275635636753619844}, 'section': 'Section::::Abstract.'}]}]