Option 1 -> Incorrectly matches "take the bull by the horns" with arguing opposing viewpoint instead of confronting challenge.
Option 2 -> Correctly matches all idioms: (A) confronting challenge, (B) arguing opposing viewpoint, (C) producing applause/laughter, (D) taking great trouble.
Option 3 -> Incorrectly matches "play the devil's advocate" with confronting challenge and "bring the house down" with taking trouble.
Option 4 -> Incorrectly matches all idioms with wrong meanings.
Hence, Option 2: (A) - (III), (B) - (IV), (C) - (i), (D) - (II) -> "Take the bull by the horns" means to face difficulties head-on with determination; "play the devil's advocate" means to argue the opposite side to stimulate discussion; "bring the house down" means to receive enthusiastic audience response; and "bend over backwards" means to make extraordinary efforts to help or accommodate -> correct