CREATE TABLE table_3159 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "U.S. viewers  ( millions ) " TEXT)

What was the title of the episode having exactly 9.64 million US viewers?
SELECT "Title" FROM table_3159 WHERE "U.S. viewers (millions)" = '9.64'
SELECT "Title" FROM "table_3159" WHERE "U.S. viewers (millions)" = '9.64'