Question: what is the s p 500 ticker symbol
[{'answer': '^ GSPC'}, {'answer': 'INX', 'provenance': [{'wikipedia_id': '170992', 'title': 'S&P 500 Index', 'start_paragraph_id': 2, 'start_character': 502, 'end_paragraph_id': 2, 'end_character': 505, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '$ SPX', 'provenance': [{'wikipedia_id': '170992', 'title': 'S&P 500 Index', 'start_paragraph_id': 2, 'start_character': 515, 'end_paragraph_id': 2, 'end_character': 520, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '170992', 'title': 'S&P 500 Index', 'start_paragraph_id': 2, 'start_character': 4, 'end_paragraph_id': 2, 'end_character': 551, 'bleu_score': 0.9126673033929591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9753278800947419435}, 'section': 'Section::::Abstract.'}]}]