Question: this composer was known for ballet symphonic works and american nationalism
[{'answer': 'Aaron Copland', 'provenance': [{'wikipedia_id': '51298', 'title': 'Aaron Copland', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 13, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '51298', 'title': 'Aaron Copland', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 917, 'bleu_score': 0.944843041139333, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4661422376466022821}, 'section': 'Section::::Abstract.'}]}]