A letter series is given with one term missing. Choose the correct alternative that will complete the sequence: IGT, JHS, KIR, LJQ, MKP, ?

Introduction / Context:
This question presents an alphabetical series of three-letter groups with one term missing. You must determine the underlying pattern in each letter position and then extend the series. The sequence to be analysed is IGT, JHS, KIR, LJQ, MKP, ?.

Given Data / Assumptions:

• Given terms: IGT, JHS, KIR, LJQ, MKP, ?
• Each term contains three letters.
• The pattern is assumed to be consistent across all positions.
• Standard alphabet positions: A = 1, ..., Z = 26.

Concept / Approach:
We examine the first, second and third letters separately. By converting letters to numbers we look for simple arithmetic changes from one term to the next in each position. If all three positions show clear patterns, we can safely extend the sequence by one step to find the missing group.

Step-by-Step Solution:
Step 1: First letters: I, J, K, L, M. Positions: I = 9, J = 10, K = 11, L = 12, M = 13. They increase by +1 at each step. Step 2: The next first letter after M (13) is 13 + 1 = 14, which is N. Step 3: Second letters: G, H, I, J, K. Positions: G = 7, H = 8, I = 9, J = 10, K = 11. These also increase by +1 each time. Step 4: The next second letter after K (11) is 11 + 1 = 12, which is L. Step 5: Third letters: T, S, R, Q, P. Positions: T = 20, S = 19, R = 18, Q = 17, P = 16. These decrease by 1 each time. Step 6: The next third letter after P (16) is 16 - 1 = 15, which is O. Step 7: Combining these gives N (first position), L (second position), O (third position). The missing term is NLO.

Verification / Alternative check:
Write the full series numerically: IGT (9,7,20), JHS (10,8,19), KIR (11,9,18), LJQ (12,10,17), MKP (13,11,16), NLO (14,12,15). The first column increases by +1, the second column increases by +1, while the third column decreases by 1 at each step. Therefore NLO fits perfectly as the next term.

Why Other Options Are Wrong:
Option A (LOP): Here the first letter L does not continue the +1 sequence beyond M. Option B (NOP): Although N is correct as a first letter, the second letter O is not the +1 progression from K, and the last letter P is not consistent with the decreasing third-letter pattern. Option D (LNO): This rearranges letters incorrectly and breaks both the second-position and third-position rules.

Common Pitfalls:
Some candidates attempt to see the pattern only in the first letters and ignore the remaining positions, leading to partial matches that are actually incorrect. Others misread the direction of change (increasing versus decreasing). Always treat each column as an independent numeric series and verify that all three are satisfied before selecting your answer.

Final Answer:
The group of letters that correctly completes the series is NLO, which corresponds to option C.