In this alphabet pattern reasoning question, select the odd group of letters from the following options: ADG, HKN, RUY and GJM.

Introduction / Context:
This question tests your ability to identify patterns in groups of letters based on their positions in the English alphabet. You are given four groups ADG, HKN, RUY and GJM and asked to select the odd group of letters. In three groups, the letters follow a simple and consistent pattern of equal steps forward in the alphabet, while one group breaks this pattern. Recognizing these steps is the key to solving the problem.

Given Data / Assumptions:

• Letter groups: ADG, HKN, RUY and GJM.
• Alphabet positions: A = 1, B = 2, ..., Z = 26.
• We focus on the differences between consecutive letters in each group.
• Exactly one group does not follow the common step size used in the others.

Concept / Approach:
We convert each letter into its numerical position in the alphabet and then calculate the differences between consecutive letters within the same group. If three groups have the same difference pattern, for example +3 and +3, and one group has a different set of differences, that group is the odd one out. This is a very common pattern in alphabet based odd one out questions.

Step-by-Step Solution:
Step 1: Analyze ADG.A = 1, D = 4, G = 7. Differences: 1 to 4 = +3, 4 to 7 = +3. So ADG follows a +3, +3 pattern.Step 2: Analyze HKN.H = 8, K = 11, N = 14. Differences: 8 to 11 = +3, 11 to 14 = +3. HKN also follows a +3, +3 pattern.Step 3: Analyze GJM.G = 7, J = 10, M = 13. Differences: 7 to 10 = +3, 10 to 13 = +3. So GJM again follows a +3, +3 pattern.Step 4: Analyze RUY.R = 18, U = 21, Y = 25. Differences: 18 to 21 = +3, 21 to 25 = +4. Here the pattern is +3, +4, which does not match the consistent +3, +3 pattern of the other three groups.Step 5: Identify the odd group.RUY is the only group in which the step sizes between letters are not equal, so it is the odd group out.

Verification / Alternative check:
If you write the letters of each group on a number line of alphabet positions, ADG, HKN and GJM all look like a regular arithmetic progression of length three with common difference 3. RUY, however, is not an arithmetic progression because 18, 21 and 25 do not have equal spacing. This visual check confirms that RUY is structurally different from the others and therefore is the intended odd one out.

Why Other Options Are Wrong:
ADG: Follows a perfect +3, +3 step pattern in the alphabet.
HKN: Also shows the same +3, +3 progression and is consistent with ADG and GJM.
GJM: Again matches the pattern of equal forward jumps of three positions, so it is not the odd one.

Common Pitfalls:
Some learners may try to interpret the groups as abbreviations or may only compare first and last letters without checking the internal differences. In alphabet reasoning questions, the internal structure of the sequence is crucial. Always compute all steps between consecutive letters to uncover the rule that the examiner is using. This habit prevents you from missing subtle changes such as the shift from +3 to +4 seen in RUY.

Final Answer:
The odd group of letters is RUY, because it follows a pattern of +3 then +4, while ADG, HKN and GJM all follow a consistent +3, +3 pattern in the alphabet.