In this letter analogy question, select the related group of letters from the given alternatives: PZQW : NXOU :: FISK : ?

Introduction / Context:
This is a classic alphabetical analogy question from verbal reasoning. The pair PZQW : NXOU shows a particular letter coding pattern, and you must apply the same pattern to the second term FISK to find the missing code. Such questions test how quickly you can see consistent shifts in letter positions inside the English alphabet and then generalize that logic to a new group of letters.

Given Data / Assumptions:
- The alphabet is considered in normal order from A to Z, numbered A = 1, B = 2, ..., Z = 26.
- The first pair PZQW and NXOU follows a single uniform pattern that affects each letter of the group.
- The same pattern must be applied to FISK to obtain the correct answer group of four letters.
- Only one option among the given choices will exactly fit the discovered pattern.

Concept / Approach:
In letter analogy questions, the main idea is to convert letters into their alphabetical positions, examine the numeric relationship, and then re convert the result back to letters. We usually look for fixed shifts such as +1, -2, +5, or similar. Once we know how each letter in the first term transforms into the corresponding letter in the second term, we must apply this same transformation, position by position, to the new term. Consistency of the shift for all positions confirms that the discovered pattern is correct.

Step-by-Step Solution:
Step 1: Write the alphabetical positions of PZQW. P = 16, Z = 26, Q = 17, W = 23. Step 2: Write the alphabetical positions of NXOU. N = 14, X = 24, O = 15, U = 21. Step 3: Compare corresponding letters: 16 to 14 is -2, 26 to 24 is -2, 17 to 15 is -2, and 23 to 21 is -2. So every letter is shifted 2 positions backward in the alphabet. Step 4: Now write the positions of FISK. F = 6, I = 9, S = 19, K = 11. Step 5: Apply the same -2 shift to each: 6 - 2 = 4 (D), 9 - 2 = 7 (G), 19 - 2 = 17 (Q), 11 - 2 = 9 (I). Step 6: Therefore FISK becomes DGQI when the same pattern is applied.

Verification / Alternative check:
To verify, apply the rule again to confirm consistency. Starting from DGQI and adding 2 to each position should bring back FISK. D (4) plus 2 gives F (6), G (7) plus 2 gives I (9), Q (17) plus 2 gives S (19), and I (9) plus 2 gives K (11). This reverse check confirms that the backward shift of 2 positions is correct and that DGQI is the only group of letters that exactly follows the same pattern used between PZQW and NXOU.

Why Other Options Are Wrong:
Option A "EFPJ" does not maintain a consistent -2 shift from FISK and produces different positional changes for individual letters.
Option B "FERI" also results from an inconsistent pattern and does not match the uniform backward shift of 2 positions for all letters.
Option D "HKVM" requires some letters to move forward instead of backward, which breaks the discovered rule. Hence these alternatives do not mirror the PZQW to NXOU relationship.

Common Pitfalls:
A common mistake is to look only at one or two letters and assume a pattern without checking all positions. Another error is mixing forward and backward shifts in order to force fit one of the options. In standardized exams, the coding rule must be uniform across every letter in the group. Always verify the pattern from the first pair and then apply it carefully to the second term.

Final Answer:
The correct related group of letters is DGQI.