CREATE TABLE table_18239 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

Who were the candidates when Lamar S. Smith was incumbent?
SELECT "Candidates" FROM table_18239 WHERE "Incumbent" = 'Lamar S. Smith'
SELECT "Candidates" FROM "table_18239" WHERE "Incumbent" = 'Lamar S. Smith'