CREATE TABLE table_31394 ("No. in series" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" FLOAT, "U.S. viewers  ( million ) " TEXT)

Who directed the episode that was watched by 2.97 million U.S. viewers?
SELECT "Directed by" FROM table_31394 WHERE "U.S. viewers (million)" = '2.97'
SELECT "Directed by" FROM "table_31394" WHERE "U.S. viewers (million)" = '2.97'