CREATE TABLE table_17953 ("Season" TEXT, "Airdate" TEXT, "The Mole" TEXT, "Winner" TEXT, "Runner-up" TEXT, "Prize money" TEXT, "International destination" TEXT)

what's runner-up with season being season 13
SELECT "Runner-up" FROM table_17953 WHERE "Season" = 'Season 13'
SELECT "Runner-up" FROM "table_17953" WHERE "Season" = 'Season 13'