In this letter coding analogy, PRAG is related to QTDK by a certain positional pattern; using the same pattern, find the group of letters that should correspond to STOP: PRAG : QTDK :: STOP : ?

Introduction / Context:
This question belongs to the letter coding and analogy section in aptitude tests. We are given an example pair PRAG : QTDK and must identify the same pattern applied to the word STOP. Understanding how each letter of PRAG is transformed into QTDK helps us derive the correct coded form of STOP from the options.

Given Data / Assumptions:

• The alphabet is ordered from A = 1 to Z = 26.
• The first pair PRAG : QTDK represents a consistent transformation applied letter by letter.
• The same transformation must be applied to STOP.
• Only one option will follow the exact same stepwise letter shift.

Concept / Approach:
The standard method for such problems is to convert letters into their numeric positions and observe the changes. We test whether each letter of PRAG is shifted by a certain number of positions to get the corresponding letter in QTDK. If we find a regular pattern, we then apply these shifts to the letters in STOP in the same order. The goal is to find a simple and consistent rule that fits all positions in the first pair.

Step-by-Step Solution:
Step 1: Write the positions for PRAG: P = 16, R = 18, A = 1, G = 7.Step 2: Write the positions for QTDK: Q = 17, T = 20, D = 4, K = 11.Step 3: Calculate the shifts for each position: P (16) to Q (17) is +1; R (18) to T (20) is +2; A (1) to D (4) is +3; G (7) to K (11) is +4.Step 4: Observe the pattern: we add +1 to the first letter, +2 to the second, +3 to the third and +4 to the fourth.Step 5: Now apply the same pattern to STOP. Positions are S = 19, T = 20, O = 15, P = 16.Step 6: Add +1 to S (19) to get 20, which is T; add +2 to T (20) to get 22, which is V; add +3 to O (15) to get 18, which is R; add +4 to P (16) to get 20, which is T.Step 7: The resulting coded form is TVRT, which matches option C.

Verification / Alternative check:
To verify, we can quickly rewrite both transformations in parallel. For PRAG, successive additions of +1, +2, +3 and +4 produce QTDK. For STOP, the same sequence of additions gives TVRT. None of the other options show this exact pattern, which confirms that TVRT is uniquely correct.

Why Other Options Are Wrong:
Option A, LMNP, does not result from adding consecutive positive integers to the positions of S, T, O and P. Option B, BDFE, would require very large backward shifts, which are inconsistent with the forward progression observed in the first pair. Option D, QSTG, mixes some letters near the original word but fails to follow the specific +1, +2, +3, +4 rule. Therefore, these options do not satisfy the discovered pattern.

Common Pitfalls:
Candidates sometimes try to apply a uniform shift to all letters or guess by visual similarity instead of carefully examining each positional change. Another common mistake is forgetting that shifts can vary from position to position in a consistent way. To avoid these pitfalls, always compute and compare the numeric positions for each letter in the example pair before moving to the second pair.

Final Answer:
The group of letters that correctly completes the analogy is TVRT, so option C is correct.