Option 1 -> (A)-(I), (B)-(II), (C)-(III), (D)-(IV) - Incorrect matching as "get into the swing of things" doesn't mean following wrong course, and other pairings are misaligned.
Option 2 -> (A)-(II), (B)-(I), (C)-(IV), (D)-(III) - Correct matching: "swing of things" = fit into rhythm; "bark up wrong tree" = wrong course; "build on sand" = without support; "blow whistle" = expose schemes.
Option 3 -> (A)-(I), (B)-(II), (C)-(IV), (D)-(III) - Incorrect as (A) and (B) are wrongly matched from the start.
Option 4 -> (A)-(III), (B)-(IV), (C)-(I), (D)-(II) - Completely incorrect alignment of all idioms with their meanings.
Hence, Option 2: (A)-(II), (B)-(I), (C)-(IV), (D)-(III) -> "Get into the swing of things" means to adapt and fit into the rhythm; "bark up the wrong tree" means pursuing the wrong approach; "build on sand" refers to creating something without solid foundation; and "blow the whistle" means to expose wrongdoing -> correct