In this alphabet sequence odd one out question, select the letter triplet that does not follow the +1 and +2 forward movement rule in the alphabet among LMO, PQS, XYB and DEG.

Introduction / Context:
This problem is an alphabet sequence odd one out question. The focus is on identifying which of the given three letter sequences does not follow a common pattern of incremental steps in the alphabet. Such questions sharpen a candidate understanding of the alphabet as a numerical sequence and their ability to detect regular jumps between letters.

Given Data / Assumptions:

• The letter triplets are LMO, PQS, XYB and DEG.
• We use alphabetical positions: A = 1, B = 2, ..., Z = 26.
• The pattern to check involves differences between consecutive letters.

Concept / Approach:
The approach is to convert each letter to its numerical position and compute the difference between the first and second letter, and between the second and third letter. If three triplets follow a consistent pattern of +1 and +2, while one triplet does not, the non conforming triplet is the odd one out.

Step-by-Step Solution:
Step 1: For LMO, L is 12, M is 13 and O is 15. Differences are 13 - 12 = 1 and 15 - 13 = 2.Step 2: For PQS, P is 16, Q is 17 and S is 19. Differences are 17 - 16 = 1 and 19 - 17 = 2.Step 3: For DEG, D is 4, E is 5 and G is 7. Differences are 5 - 4 = 1 and 7 - 5 = 2.Step 4: For XYB, X is 24, Y is 25 and B is 2. Differences if we move forward in the alphabet are 25 - 24 = 1 and 2 - 25, which does not equal 2 and also implies wrapping around the alphabet, breaking the simple +1 and +2 pattern.Step 5: Since LMO, PQS and DEG all follow the pattern first difference = +1 and second difference = +2, while XYB does not, XYB is the odd one out.
Verification / Alternative check:
You can think of each correct sequence as stepping to the very next letter and then skipping one letter. For example, L to M is immediate next and M to O skips N. Exactly the same style holds for PQS and DEG. XYB, however, would require wrap around from Y to B and does not produce a simple two step forward movement, so it clearly does not fit the same model.

Why Other Options Are Wrong:
LMO is not the odd one out because it follows the consistent +1, +2 pattern.
PQS also conforms exactly to the +1, +2 sequence rule in the alphabet.
DEG similarly follows the same pattern and therefore belongs with LMO and PQS.

Common Pitfalls:
Some learners may try to treat the alphabet as circular and attempt to justify XYB with complicated wrap around logic. However, in most exam questions the simplest forward pattern is intended. Another issue is confusing letter positions, especially towards the end of the alphabet. Regular practice with mapping letters to numbers can prevent such errors.

Final Answer:
The only triplet that does not follow the pattern of +1, then +2 in the alphabet is XYB, so XYB is the odd one out.