Consider the alphabetic series HZF, IWH, KSJ, NNL, and a missing term. Each term follows a particular pattern in the positions of its three letters in the English alphabet. Following the same pattern, which of the following options correctly completes the series?

Introduction / Context:
This question asks us to find the next term in a three letter alphabetic series. Such questions are based on systematic changes in the positions of letters in the alphabet across the terms. The goal is to determine the underlying rule that controls the evolution of the first, second, and third letters, and then apply that rule to find the missing term from the given answer choices.

Given Data / Assumptions:

• The given series is: HZF, IWH, KSJ, NNL, ?
• Each term has exactly three letters.
• The options for the missing term are THN, RGM, SHM, and RHN.
• We assume a regular pattern, often arithmetic, in the alphabet positions for each letter position within the terms.

Concept / Approach:
We convert letters to their alphabet positions: A is 1, B is 2, and so on up to Z as 26. Then, we look separately at the first, second, and third letters in each group, checking how their positions change from one term to the next. Typically, the pattern can be an increasing or decreasing sequence, sometimes with different increments, for each letter position. Once the pattern is recognized, we apply it to the last known term to predict the next term.

Step-by-Step Solution:
Step 1: First letters: H, I, K, N. Positions are H=8, I=9, K=11, N=14. Differences are +1, +2, +3. The next difference should be +4, so 14 + 4 = 18, which is R.Step 2: Second letters: Z, W, S, N. Positions are Z=26, W=23, S=19, N=14. Differences are -3, -4, -5. The pattern suggests decreasing differences, so next should be -6. Therefore, 14 - 6 = 8, which corresponds to H.Step 3: Third letters: F, H, J, L. Positions are F=6, H=8, J=10, L=12, which increase by +2 each time. The next term should therefore be 12 + 2 = 14, which is N.Step 4: Combining the deduced letters, the missing term is R H N.Step 5: Among the options, RHN exactly matches this pattern, confirming it as the correct answer.

Verification / Alternative check:
We can double check by confirming that no other option fits all three independent sequences. THN has T as its first letter, which would require a jump of +6 from N, breaking the increasing increment rule. RGM does not give the correct decreasing sequence for the second letter, and SHM fails both the first and second letter patterns. Only RHN maintains the evolving differences of +1, +2, +3, +4 for the first letters, -3, -4, -5, -6 for the second letters, and +2 consistently for the third letters.

Why Other Options Are Wrong:
THN has a first letter too far ahead, RGM gives G as the second letter instead of H, which does not continue the decreasing gap pattern, and SHM fails both the required first letter and second letter progression. Since the series has a very strict arithmetic structure, even a small violation of that pattern disqualifies an option.

Common Pitfalls:
Students sometimes try to guess the answer by visual similarity alone or look only at one position, such as the first letter, without checking the other two. Another pitfall is forgetting to analyze the differences in positions rather than the raw positions. In alphabet series questions, breaking the problem into separate letter positions and tracking their numeric changes is essential.

Final Answer:
Following the pattern for all three letter positions, the correct next term in the series is RHN.