Question: what does md stand for in the united states
[{'answer': 'Doctor of Medicine degree', 'provenance': [{'wikipedia_id': '12101775', 'title': 'Comparison of MD and DO in the United States', 'start_paragraph_id': 1, 'start_character': 53, 'end_paragraph_id': 1, 'end_character': 78, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '12101775', 'title': 'Comparison of MD and DO in the United States', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 297, 'bleu_score': 0.957870874785216, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17462646378263866345}, 'section': 'Section::::Abstract.'}]}]