Classification – Odd one out (quartets – +2, +1, +2 stepping): Which string breaks the +2, +1, +2 advance between letters: BdEg, PrSu, KmNp, TwXz?

Introduction / Context:
Across these mixed-case strings, ignore case and consider letter indices. Three strings show a repeating step pattern: +2, then +1, then +2. One string starts with a larger first jump and thus violates the rule.

Given Data / Assumptions:

• B d E g → 2,4,5,7 → +2, +1, +2.
• P r S u → 16,18,19,21 → +2, +1, +2.
• K m N p → 11,13,14,16 → +2, +1, +2.
• T w X z → 20,23,24,26 → +3, +1, +2 (breaks).

Concept / Approach:
Compute the three successive steps. Only TwXz begins with +3. Because the pattern required +2 at the first step, TwXz is the odd one out.

Step-by-Step Solution:
1) Translate to indices; compute deltas.2) Compare to the target (+2, +1, +2).3) Flag TwXz for the mismatched first jump.

Verification / Alternative check:
Checking backward differences yields −2, −1, −2 for the valid strings; TwXz still does not align in reverse, corroborating the mismatch.

Why Other Options Are Wrong:
BdEg, PrSu, KmNp each fits the specified step rule exactly.

Common Pitfalls:
Letting the visual irregularity of mixed case distract from the consistent numeric pattern.

Final Answer:
TwXz