CREATE TABLE table_name_68 (dance VARCHAR, worst_dancer_s_ VARCHAR, worst_score VARCHAR)

What is the dance that has priscilla presley is the worst dancer(s), and the worst score of 21?
SELECT dance FROM table_name_68 WHERE worst_dancer_s_ = "priscilla presley" AND worst_score = "21"
SELECT "dance" FROM "table_name_68" WHERE "21" = "worst_score" AND "priscilla presley" = "worst_dancer_s_"