user: Question: How many candidates ran in the election in the Arkansas 4 district? 
Columns: ['District', 'Incumbent', 'Party', 'First elected', 'Result', 'Candidates']
Types: ['text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Arkansas 1', 'William J. Driver', 'Democratic', 1920.0, 'Re-elected', 'William J. Driver (D) Unopposed']
SQL:

assistant: SELECT COUNT("Candidates") FROM "Table" WHERE "District" = 'Arkansas 4';