Question: the main agency under the department of homeland security that is responsible for border security is
[{'answer': 'U.S. Customs and Border Protection', 'provenance': [{'wikipedia_id': '58236', 'title': 'United States Department of Homeland Security', 'start_paragraph_id': 3, 'start_character': 262, 'end_paragraph_id': 3, 'end_character': 296, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '58236', 'title': 'United States Department of Homeland Security', 'start_paragraph_id': 25, 'start_character': 26, 'end_paragraph_id': 25, 'end_character': 1120, 'bleu_score': 0.922351726925382, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11592841532624243020}, 'section': 'Section::::Function.\n'}]}]