Select the related group of letters from the given alternatives: RIGT : WDBY :: FUSH : ?

Introduction / Context:
This is an alphabetical coding analogy where two four letter groups are related by a specific pattern. The pair RIGT : WDBY follows a rule that involves both forward and backward shifts in the alphabet. Your task is to detect this consistent pattern and apply it to the letters FUSH to obtain the corresponding code. Such questions check careful observation and the ability to track patterns across multiple positions.

Given Data / Assumptions:
- Alphabet positions are A = 1 through Z = 26.
- RIGT and WDBY are related by a consistent letter wise rule across all four positions.
- The same transformation is applied to FUSH to generate the answer group.
- The options have been constructed so that only one matches this transformation exactly.

Concept / Approach:
We compare each letter from the first word RIGT with the corresponding letter in the second word WDBY. If we find a consistent numeric shift (for example +5 or -5) in the positions, that rule should apply position wise. If there is an alternating pattern, such as +5, -5, -5, +5, we must preserve that same alternation for the new word FUSH. Once we apply the rule correctly, the resulting letter group can be matched with the given options.

Step-by-Step Solution:
Step 1: Convert RIGT into positions. R = 18, I = 9, G = 7, T = 20. Step 2: Convert WDBY into positions. W = 23, D = 4, B = 2, Y = 25. Step 3: Check the shift for each position. From R (18) to W (23) is +5. From I (9) to D (4) is -5. From G (7) to B (2) is -5. From T (20) to Y (25) is +5. So the pattern is +5, -5, -5, +5. Step 4: Now convert FUSH to positions. F = 6, U = 21, S = 19, H = 8. Step 5: Apply the same pattern to FUSH. First letter: 6 + 5 = 11, which is K. Second letter: 21 - 5 = 16, which is P. Third letter: 19 - 5 = 14, which is N. Fourth letter: 8 + 5 = 13, which is M. Step 6: The coded form of FUSH is therefore KPNM.

Verification / Alternative check:
To verify, reverse the transformation on KPNM using -5, +5, +5, -5 respectively. K (11) minus 5 becomes F (6). P (16) plus 5 becomes U (21). N (14) plus 5 becomes S (19). M (13) minus 5 becomes H (8). This gives back FUSH, confirming that the pattern has been applied correctly. None of the other options produce FUSH when the inverse transformation is applied, so KPNM is uniquely correct.

Why Other Options Are Wrong:
Option B "PKNM" has the same letters but in a different order and does not follow the exact +5, -5, -5, +5 sequence from FUSH.
Option C "KPMN" again rearranges the letters and breaks the precise position wise mapping, so it cannot come from the given rule.
Option D "JQML" would require uneven shifts of varying sizes that do not match the neat pattern discovered between RIGT and WDBY.

Common Pitfalls:
Learners sometimes focus only on the magnitude of the shift and ignore its direction, which leads to mixing up +5 and -5. Another common error is to treat the group of letters as a whole rather than checking each position separately. For multi letter codes, always verify the transformation at every position before selecting an answer.

Final Answer:
The correct coded form of FUSH is KPNM.