user: Question: Who were the candidates when Sid Simpson was the incumbent?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Illinois 3', 'Fred E. Busbey', 'Republican', 1942.0, 'Lost re-election Democratic gain', 'Edward A. Kelly (D) 52.0% Fred E. Busbey (R) 48.0%']
SQL:

assistant: SELECT "Candidates" FROM "Table" WHERE "Incumbent" = 'Sid Simpson';