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

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'