user: Question: Who were the candidates when Noble Jones Gregory was incumbent?
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Kentucky 1', 'Noble Jones Gregory', 'Democratic', 1936.0, 'Re-elected', 'Noble Jones Gregory (D) Unopposed']
SQL:

assistant: SELECT "Candidates" FROM "Table" WHERE "Incumbent" = 'Noble Jones Gregory';