Who directed the episode that was watched by 2.97 million U.S. viewers? 
CREATE TABLE "table1_29920800_1" (
  "no_in_series" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" real,
  "u_s_viewers_million" text
);
SELECT "directed_by" FROM "table1_29920800_1" WHERE "u_s_viewers_million"='2.97';