CREATE TABLE table_19874 ("Task No." FLOAT, "Day announced" TEXT, "Description" TEXT, "Options" TEXT, "Viewers selection" TEXT, "Result" TEXT)

What was the description when the viewers selected Nan?
SELECT "Description" FROM table_19874 WHERE "Viewers selection" = 'Nan'
SELECT "Description" FROM "table_19874" WHERE "Viewers selection" = 'Nan'