Question: who is the current secretary of department of homeland security
[{'answer': 'Kirstjen Nielsen', 'provenance': [{'wikipedia_id': '212926', 'title': 'United States Secretary of Homeland Security', 'start_paragraph_id': 2, 'start_character': 86, 'end_paragraph_id': 2, 'end_character': 102, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]