A series of three letter groups is given as dem, fgo, hiq, and one more missing term. Which of the following options correctly completes the series?

Introduction / Context:
This is a classic alphabet series question involving three letter groups. You are given three terms dem, fgo, and hiq, and you must find the next term that continues the pattern. Each position in the triplet follows a separate rule based on the positions of letters in the English alphabet. Such questions check your understanding of alphabetical order and your ability to track multiple parallel patterns at the same time.

Given Data / Assumptions:

• First term: dem.
• Second term: fgo.
• Third term: hiq.
• We need the fourth term that follows the same logical pattern as the previous ones.

Concept / Approach:
The key idea is to treat the first, second, and third letters of each group as three separate sequences. For each position, we convert the letters to their alphabet positions and look for a numeric pattern. We then apply the same increment to obtain the next letter in each position. If all three positions show a consistent rule, we can confidently generate the missing triplet. This structured approach avoids guesswork and ensures accuracy.

Step-by-Step Solution:
Step 1: Consider the first letters: d, f, h. Their positions are 4, 6, and 8, which increase by 2 each time. Step 2: The next first letter should be 8 plus 2, which is 10, corresponding to j. Step 3: Consider the second letters: e, g, i with positions 5, 7, and 9, again increasing by 2 each time. Step 4: The next second letter should be 9 plus 2, that is 11, corresponding to k. Step 5: Consider the third letters: m, o, q with positions 13, 15, and 17, increasing by 2 each time. Step 6: The next third letter should be 17 plus 2, which is 19, corresponding to s, so the required group is jks.

Verification / Alternative check:
We can quickly verify the choice jks by checking the increments again. For each position, we add 2 to the alphabet index and confirm that we obtain the letters in our answer. There is no deviation in the increment pattern, and the difference remains constant across all three positions. None of the other options produce consistent increments of plus two for every corresponding position of the triplets, which confirms that jks is the only valid continuation of the sequence.

Why Other Options Are Wrong:
Option A (jkt) has the correct first two letters j and k but ends with t, which represents position 20, not 19, and therefore breaks the plus two rule in the third position. Option B (ikp) changes the increments in more than one position and does not respect the constant difference of two. Option D (klt) alters both the starting letter and the pattern and fails to match any consistent progression from the previous terms. Thus none of these options aligns with the clear arithmetic structure observed in the series.

Common Pitfalls:
Learners sometimes focus only on visually similar letters or on one position of the triplet and ignore the others. This can lead to choosing an option that appears partially correct but fails under closer inspection. Another frequent mistake is to miscount letter positions in the alphabet, especially for letters nearer to the end. Writing down the index numbers and verifying the difference between consecutive terms helps avoid these errors and leads to a systematic solution.

Final Answer:
The correct missing term is jks, which corresponds to option C.