In the triplet series ENG, GQI, ITK, KWM, which of the following three letter groups should come next to correctly extend the alphabet pattern?

Introduction / Context:
This series uses three letter groups where each position follows a separate numeric progression. The letters move forward in the alphabet by different constant steps, which is typical of many alphabet series questions in aptitude exams. Solving it requires you to track the three progressions in parallel and to apply arithmetic reasoning in the context of the alphabet.

Given Data / Assumptions:
- Given series: ENG, GQI, ITK, KWM, ? - Each term is a group of three capital letters. - The same pattern holds for each position throughout the series. - Alphabet positions: A = 1, B = 2, ..., Z = 26.

Concept / Approach:
We treat the first, second, and third letters of the triplets as independent sequences. For each sequence, we convert letters to numbering from 1 to 26, calculate the differences between consecutive terms, and look for constant increments. Once we know how each position progresses, we apply that rule once more to obtain the next numeric position. We then convert those positions back into letters to construct the missing triplet in the series.

Step-by-Step Solution:
Step 1: Convert letters into numeric positions. ENG: E (5), N (14), G (7). GQI: G (7), Q (17), I (9). ITK: I (9), T (20), K (11). KWM: K (11), W (23), M (13). Step 2: Analyse the first letters sequence: E, G, I, K. Positions: 5, 7, 9, 11. Each step increases by +2. Next first letter: 11 + 2 = 13, which is M. Step 3: Analyse the second letters sequence: N, Q, T, W. Positions: 14, 17, 20, 23. span style="display:block;">Again each step is +3. Next second letter: 23 + 3 = 26, which corresponds to Z. Step 4: Analyse the third letters sequence: G, I, K, M. Positions: 7, 9, 11, 13. Each step increases by +2. Next third letter: 13 + 2 = 15, which is O. Step 5: Combine the three predicted letters. First letter M, second letter Z, third letter O, giving MZO.

Verification / Alternative check:
We can summarise the sequences numerically: First position: 5, 7, 9, 11, 13 (+2 each). Second position: 14, 17, 20, 23, 26 (+3 each). Third position: 7, 9, 11, 13, 15 (+2 each). The symmetry of these progressions and the clean arithmetic confirm that MZO is the correct extension. Among the provided options, only MZO has M in the first position, Z in the second, and O in the third, matching the predicted numeric pattern exactly.

Why Other Options Are Wrong:
A) NAP uses N for the first letter instead of M and does not respect the +2 rule for the first position. C) MAO has M and O in the first and third positions but uses A (1) instead of Z (26) in the second position. D) NZP fails for both the second and third positions, as neither Z nor P fit the +3 and +2 sequences from the previous term.

Common Pitfalls:
Some exam takers may recognise that the first and third letters move by +2 but fail to consider that the second letter uses a different step size. Others might miscount positions, especially near the higher letters like W and Z. To avoid such mistakes, consistently convert letters to numbers and check differences step by step. Also, always consider that different positions in a triplet may follow different arithmetic progressions in multi position series problems.

Final Answer:
The three letter group that correctly completes the series ENG, GQI, ITK, KWM, ? is MZO.