Find the odd mixed-case triple (constant +5, +5 steps): Pick the item that breaks the equal forward steps between letters.

Introduction / Context:
Case (upper/lower) can distract from the underlying arithmetic. By mapping letters to indices regardless of case, we can test whether a constant forward step (e.g., +5) is applied twice in succession.

Given Data / Assumptions:

• MrW: M→r (13→18, +5), r→W (18→23, +5) → fits.
• KpU: K→p (11→16, +5), p→U (16→21, +5) → fits.
• BgL: B→g (2→7, +5), g→L (7→12, +5) → fits.
• ChN: C→h (3→8, +5), h→N (8→14, +6) → breaks (second step +6).

Concept / Approach:
Ignore case; compute numerical differences only. The outlier is the only triple whose second step is not +5.

Step-by-Step Solution:

Verification / Alternative check:
Visual alignment on an alphabet ruler shows equal spacing for three items and a wider final gap for the outlier.

Why Other Options Are Wrong:
They maintain +5 spacing consistently.

Common Pitfalls:
Do not treat case changes as separate alphabets; the index positions are identical.

Final Answer:
ChN