All-Distinct Lullaby

**Scenario.** A candidate solution passed 500 random tests, all with distinct values. Which category should you test FIRST? **Which approach is the best fit? The program only needs to print the letter.** **A)** Signed overflow — always first **B)** Tie-breaking — all-distinct data cannot exercise equal-key branches, so those paths are completely untested **C)** Direction confusion **D)** Ordered/unordered counting