What was the score for the match that had the result of Hunter Mariners def. Castleford Tigers?
CREATE TABLE "round_2" (
  "date" text,
  "result" text,
  "score" text,
  "stadium" text,
  "city" text,
  "crowd" real
);
SELECT "score" FROM "round_2" WHERE "result"='hunter mariners def. castleford tigers';