Question: the orchestra has how many primary instrument groups
[{'answer': 'four', 'provenance': [{'wikipedia_id': '22706', 'title': 'Orchestra', 'start_paragraph_id': 15, 'start_character': 43, 'end_paragraph_id': 15, 'end_character': 47, 'bleu_score': 1.0, 'section': 'Section::::Instrumentation.\n'}]}, {'provenance': [{'wikipedia_id': '22706', 'title': 'Orchestra', 'start_paragraph_id': 15, 'start_character': 0, 'end_paragraph_id': 15, 'end_character': 445, 'bleu_score': 0.875422429599466, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6811366561945059425}, 'section': 'Section::::Instrumentation.\n'}]}]