Each of the following options is a group of four capital letters. In three of the groups, the third letter is exactly two positions ahead of the first letter in the English alphabet. In which group does this pattern break, making it the odd one out: RGTF, MLOK, CTES, VDZC?

Introduction / Context:
Letter based odd one out questions test knowledge of the alphabetical order and the ability to spot consistent positional patterns. In this problem, each option is a group of four letters. The hint given in the wording is that the third letter in three of the groups is two positions ahead of the first letter in the alphabet, and we must find the group that does not follow this pattern.

Given Data / Assumptions:

• Groups: RGTF, MLOK, CTES, and VDZC.
• We consider positions of letters in the English alphabet: A as 1, B as 2, and so on up to Z as 26.
• We focus on the relation between the first and the third letter in each group.
• The odd group is the one in which this relation does not match the others.

Concept / Approach:
We convert each letter to its numerical position. For each group, we note the positions of the first and third letters and then compute the difference third minus first. If the difference is consistently 2 for three options and different for one option, that option is the odd one out. This direct application of letter position arithmetic makes the pattern clear and objective.

Step-by-Step Solution:
Step 1: For RGTF, the letters R and T are the first and third letters. R is the 18th letter, and T is the 20th letter. The difference is 20 − 18 = 2. Step 2: For MLOK, the letters M and O are the first and third letters. M is 13, and O is 15, so the difference is 15 − 13 = 2. Step 3: For CTES, the letters C and E are the first and third letters. C is 3, and E is 5, so the difference is 5 − 3 = 2. Step 4: For VDZC, the letters V and Z are the first and third letters. V is 22, and Z is 26, giving a difference of 26 − 22 = 4. Step 5: We observe that in three groups the first and third letters differ by exactly 2 positions, while in VDZC the difference is 4. Thus, VDZC breaks the pattern.

Verification / Alternative check:
To check quickly, we can write a compact representation for each group: RGTF as R_2_T, MLOK as M_2_O, CTES as C_2_E, and VDZC as V_4_Z, where the number indicates the gap between first and third letters. Only VDZC shows a gap of 4, confirming that it does not follow the same rule as the other three groups. No other simple relation, such as between second and fourth letters, yields such a clean pattern.

Why Other Options Are Wrong:
RGTF: Follows the pattern first letter plus two positions equals third letter (R to T), so it is not odd.
MLOK: Also follows the same pattern, with M to O being a two position jump.
CTES: Again satisfies the condition, with C to E as a two position jump.
None of the above: This would be correct only if no letter group broke the pattern, which is not the case.

Common Pitfalls:
Some learners may focus on relationships between other pairs of letters or on the full group instead of the key first third relation, which can hide the simple pattern. Another mistake is mis counting the positions of letters in the alphabet, especially near the end with letters like V, X, and Z. Writing down the positions or using a quick mental mapping helps avoid such errors.

Final Answer:
The only letter group that does not have the third letter exactly two positions ahead of the first letter is VDZC, so it is the odd one out.