In the alphabet series K, J, L, I, M, which letter should appear next to correctly extend the pattern?

Introduction / Context:
This question involves a single letter series where the pattern is not a simple constant step, but an alternating set of positive and negative jumps with increasing magnitude. Competitive exam setters often use such mixed step series to test whether you notice the pattern of differences rather than only looking at the letters. Recognising changes in both sign and size of the step is crucial for these problems.

Given Data / Assumptions:
- Given series: K, J, L, I, M, ? - Only capital Latin letters are used. - Alphabet positions: A = 1, B = 2, ..., Z = 26. - We assume a single continuous pattern governs successive differences.

Concept / Approach:
We convert letters to their corresponding numeric positions and analyse the differences between consecutive terms. Here the series is likely to involve alternating increases and decreases with a growing step size. Once we identify the pattern in the sequence of differences, we can extend it to find the next numeric value. Finally, we map this value back to a letter to get the required term. It is important not to jump to conclusions based on only the first or last difference; instead, observe several consecutive steps.

Step-by-Step Solution:
Step 1: Convert letters to numbers. K = 11, J = 10, L = 12, I = 9, M = 13. Step 2: Compute differences between consecutive terms. From K (11) to J (10): difference = -1. From J (10) to L (12): difference = +2. From L (12) to I (9): difference = -3. From I (9) to M (13): difference = +4. Step 3: Observe the pattern of differences. The signs alternate negative, positive, negative, positive. The magnitudes increase by 1 each time: 1, 2, 3, 4. Step 4: Extend the pattern to predict the next difference. Following the sequence, the next step should be negative with magnitude 5, that is -5. Step 5: Apply the predicted difference to the last term. Current last term M is 13, so 13 - 5 = 8. Position 8 corresponds to the letter H.

Verification / Alternative check:
If we list numbers and differences together, we have: 11, 10, 12, 9, 13, 8 with differences -1, +2, -3, +4, -5. These differences are perfectly consistent with the rule of alternating signs and steadily increasing magnitude. No other candidate letter generates this exact continuation. If any other option were used, the difference from M would not match the expected -5, and the alternating pattern would break. Hence, H is fully justified by the observed structure of the series.

Why Other Options Are Wrong:
A) G has position 7, which gives a difference of -6 from M, not -5, so it does not follow the pattern. C) F has position 6, producing a gap of -7, which is even further from the required magnitude. D) N has position 14, which would give +1 from M; this breaks both the sign and magnitude progression.

Common Pitfalls:
Some learners only look for constant differences and conclude there is no pattern, or they guess based on rough letter spacing. Others may see only the magnitudes 1, 2, 3, 4 and forget to pay attention to the sign changes. A consistent method is to write every difference with its sign and value, then look for regular alternation and gradual changes. This disciplined approach uncovers hidden series structures and improves accuracy in reasoning questions.

Final Answer:
The letter that correctly continues the series K, J, L, I, M, ? is H.