Question: what do the stars on the chicago flag represent
[{'answer': 'Fort Dearborn', 'provenance': [{'wikipedia_id': '1213698', 'title': 'Flag of Chicago', 'start_paragraph_id': 2, 'start_character': 512, 'end_paragraph_id': 2, 'end_character': 525, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'the Great Chicago Fire of 1871'}, {'answer': 'the Century of Progress Exposition ( 1933 -- 34 )'}, {'answer': "the World 's Columbian Exposition of 1893"}]