Question: who acts as the gatekeeper in a health maintenance organization (hmo)
[{'answer': 'doctor', 'provenance': [{'wikipedia_id': '59097', 'title': 'Health maintenance organization', 'start_paragraph_id': 1, 'start_character': 359, 'end_paragraph_id': 1, 'end_character': 365, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '59097', 'title': 'Health maintenance organization', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 841, 'bleu_score': 0.9850176677359421, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4431419619250356105}, 'section': 'Section::::Operation.\n'}]}]