In this letter pair analogy, UCG is related to WEI by a fixed forward shift in the alphabet. Using the same pattern, which pair correctly completes the analogy for the missing term?

Introduction / Context:
This is a letter pair analogy involving three letter groups. The given example UCG : WEI indicates a specific pattern of alphabet shifts that transforms each letter of the first group into the corresponding letter of the second group. Your task is to identify which of the answer pairs follows the same pattern between its two three letter groups, thereby preserving the logic of the analogy. Such questions test systematic thinking with letter positions and consistent increments.

Given Data / Assumptions:

We have the example mapping UCG to WEI.
The analogy format is UCG : WEI :: ? : ? and we must choose the correct pair from the options.
Options are RPC : TRE, PWC : RYD, JLR : KNT and LPJ : NQL.
We use the standard alphabet A to Z mapped to positions 1 to 26.
We assume the transformation is position based and letter order is not rearranged.

Concept / Approach:
The approach is to convert letters to their numeric positions and observe the differences between corresponding letters. For UCG to WEI, we compare U with W, C with E and G with I. If we find the same shift in all three positions, we conclude that the rule is a uniform Caesar style shift. After discovering this shift, we test each option to see which one shows the same differences between its first and second group, thus following the same coding pattern.

Step-by-Step Solution:
Step 1: Write positions of U, C and G. U = 21, C = 3, G = 7. Step 2: Write positions of W, E and I. W = 23, E = 5, I = 9. Step 3: Compute the differences: 23 - 21 = 2, 5 - 3 = 2, 9 - 7 = 2. Each letter in UCG is shifted forward by two positions to obtain WEI. Step 4: Conclude that the rule is “add 2 to the position of every letter”. Step 5: Now test option A, RPC : TRE. R = 18, P = 16, C = 3 and T = 20, R = 18, E = 5. Step 6: Check differences: 20 - 18 = 2, 18 - 16 = 2, 5 - 3 = 2. Every letter is again shifted by plus two. Step 7: Therefore RPC : TRE follows exactly the same +2 shift pattern as UCG : WEI.

Verification / Alternative check:
For completeness, we can briefly check that the other options do not follow a uniform plus two shift. In PWC : RYD, P to R is plus two, but W to Y is also plus two and C to D is plus one, so the pattern breaks. In JLR : KNT, J to K is plus one, L to N is plus two, R to T is plus two, so the shift is not consistent across all positions. In LPJ : NQL, L to N is plus two, P to Q is plus one and J to L is plus two, again inconsistent. Only RPC : TRE maintains the same plus two movement for every corresponding position as UCG : WEI does.

Why Other Options Are Wrong:
PWC : RYD fails because the last letter shift C to D is different from the first two shifts. JLR : KNT mixes plus one and plus two shifts, which does not match a strict Caesar shift. LPJ : NQL also mixes shifts and does not maintain a constant difference between all corresponding letters. A valid analogy requires the same transformation at each position and in each pair, which these alternatives do not satisfy.

Common Pitfalls:
Candidates sometimes spot one or two matching shifts and assume the whole option is correct without checking every letter. Another common error is to compare only the first letters of each group. To avoid this, always calculate the difference for each position and confirm that the same rule applies uniformly. Recognising common patterns such as constant additions or subtractions can speed up your analysis, but it is important to verify the pattern completely before choosing an answer.

Final Answer:
Since UCG is coded to WEI by shifting each letter two steps forward, the only option that follows the same rule is RPC : TRE, so that pair correctly completes the analogy.