Question: which circuit is the first stage of a dc power supply
[{'answer': 'the rectifier circuit', 'provenance': [{'wikipedia_id': '223407', 'title': 'Switched-mode power supply', 'start_paragraph_id': 31, 'start_character': 227, 'end_paragraph_id': 31, 'end_character': 248, 'bleu_score': 1.0, 'section': 'Section::::Theory of operation.:Input rectifier stage.\n'}]}, {'provenance': [{'wikipedia_id': '223407', 'title': 'Switched-mode power supply', 'start_paragraph_id': 31, 'start_character': 0, 'end_paragraph_id': 31, 'end_character': 1055, 'bleu_score': 0.945344916890206, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13937936278723015320}, 'section': 'Section::::Theory of operation.:Input rectifier stage.\n'}]}]