CREATE TABLE table_18241 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

Who were the candidates when Jack Fields was the incumbent?
SELECT "Candidates" FROM table_18241 WHERE "Incumbent" = 'Jack Fields'
SELECT "Candidates" FROM "table_18241" WHERE "Incumbent" = 'Jack Fields'