In this letter pair reasoning question, find the odd pair from the following options: AE, CG, JN and MO.

Introduction / Context:
This question deals with letter pairs and their spacing in the English alphabet. You are given four pairs of letters: AE, CG, JN and MO. In three of these pairs, the second letter is exactly four positions ahead of the first letter in the alphabet. One pair has a different spacing. You must determine which pair does not follow the same pattern and mark it as the odd one out.

Given Data / Assumptions:

• Letter pairs: AE, CG, JN and MO.
• We use alphabet positions: A = 1, B = 2, ..., Z = 26.
• In valid pairs, the difference between second and first letter equals 4.
• Exactly one pair does not satisfy this constant difference rule.

Concept / Approach:
We convert each letter to its position in the alphabet and compute the difference second position minus first position in each pair. If three pairs yield a difference of 4 and one pair yields a different difference, that pair is the odd one out. This type of pattern recognition is very common in letter analogy and classification questions.

Step-by-Step Solution:
Step 1: Examine AE.A = 1, E = 5. Difference is 5 - 1 = 4. So AE has a spacing of 4 letters.Step 2: Examine CG.C = 3, G = 7. Difference is 7 - 3 = 4. So CG also has a spacing of 4 letters.Step 3: Examine JN.J = 10, N = 14. Difference is 14 - 10 = 4. JN fits the same pattern.Step 4: Examine MO.M = 13, O = 15. Difference is 15 - 13 = 2. Here the spacing is only 2, not 4.Step 5: Identify the odd pair.AE, CG and JN all have a consistent gap of 4 positions between letters, while MO has a gap of 2. Therefore MO is the odd pair out.

Verification / Alternative check:
Another way to verify is to write the alphabet and count forward from each first letter. Starting from A and counting four steps forward (including the next letter) brings you to E. From C, four steps bring you to G. From J, four steps bring you to N. However, starting from M, four steps forward would bring you to Q, not O. Since O is only two positions ahead of M, this confirms that MO does not share the same spacing as the other three pairs.

Why Other Options Are Wrong:
AE: Second letter is four positions ahead of the first, fitting the common pattern.
CG: Also shows a difference of 4 between C and G, consistent with AE and JN.
JN: Once again, N is four positions ahead of J, so this pair is part of the main pattern.

Common Pitfalls:
Sometimes learners confuse counting positions and counting letters in between. The safe method is always to convert letters to numerical positions and subtract the first from the second. This eliminates counting errors and makes it easier to spot equal differences. When the pattern is based on a constant gap, even a small mistake can lead to a wrong answer, so a systematic approach is very helpful.

Final Answer:
The odd letter pair is MO, because in this pair the second letter is only two positions ahead of the first, while in the other three pairs the second letter is four positions ahead of the first.