Question: which country won the maximum number of gold medals at the london olympics 2012
[{'answer': 'United States', 'provenance': [{'wikipedia_id': '34832586', 'title': '2012 Summer Olympics medal table', 'start_paragraph_id': 2, 'start_character': 113, 'end_paragraph_id': 2, 'end_character': 126, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '34832586', 'title': '2012 Summer Olympics medal table', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 990, 'bleu_score': 0.9381859728099231, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13365630406618689848}, 'section': 'Section::::Abstract.'}]}]