Question: who are the four heads on mount rushmore
[{'answer': 'George Washington', 'provenance': [{'wikipedia_id': '185973', 'title': 'Mount Rushmore', 'start_paragraph_id': 1, 'start_character': 351, 'end_paragraph_id': 1, 'end_character': 368, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Thomas Jefferson', 'provenance': [{'wikipedia_id': '185973', 'title': 'Mount Rushmore', 'start_paragraph_id': 1, 'start_character': 382, 'end_paragraph_id': 1, 'end_character': 398, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Theodore Roosevelt', 'provenance': [{'wikipedia_id': '185973', 'title': 'Mount Rushmore', 'start_paragraph_id': 1, 'start_character': 412, 'end_paragraph_id': 1, 'end_character': 430, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Abraham Lincoln', 'provenance': [{'wikipedia_id': '185973', 'title': 'Mount Rushmore', 'start_paragraph_id': 1, 'start_character': 448, 'end_paragraph_id': 1, 'end_character': 463, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]