Question: who is the head of department of labor
[{'answer': 'Alexander Acosta', 'provenance': [{'wikipedia_id': '44275', 'title': 'United States Secretary of Labor', 'start_paragraph_id': 3, 'start_character': 106, 'end_paragraph_id': 3, 'end_character': 122, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]