Question: where does the united states rank in infant mortality rate
[{'answer': '5', 'provenance': [{'wikipedia_id': '2525954', 'title': 'List of countries by infant and under-five mortality rates', 'start_paragraph_id': 1, 'start_character': 243, 'end_paragraph_id': 1, 'end_character': 244, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]