In the alphanumeric series C11, V17, O23, which of the following terms correctly completes the pattern as the next element?

Introduction / Context:
This problem involves an alphanumeric series where each term combines a letter with a number: C11, V17, O23, ?. You must find the next combined term. Such questions usually hide one pattern in the letters and another in the numbers. Spotting both patterns is essential.

Given Data / Assumptions:

• Series: C11, V17, O23, ?
• Letters: C, V, O, ?
• Numbers: 11, 17, 23, ?
• Alphabet positions: A 1 to Z 26.
• We assume separate but consistent patterns in the letter component and the numeric component.

Concept / Approach:
We split the series into two subsequences: a letter sequence and a numeric sequence. For the numbers, we look for a simple arithmetic progression. For the letters, we look at their positions and check whether a constant difference is applied, possibly using wrap around arithmetic modulo 26. Once both rules are found, we apply them once more to obtain the next term.

Step-by-Step Solution:
Step 1: Examine the numeric sequence: 11, 17, 23. Step 2: Compute differences: 17 minus 11 equals 6, and 23 minus 17 equals 6. So the numbers form an arithmetic progression with a common difference of 6. Step 3: Continue this pattern: 23 plus 6 equals 29. Thus the next numeric part is 29. Step 4: Now examine the letters C, V, O. Convert to positions: C 3, V 22, O 15. Step 5: Compute the differences moving from left to right. From 3 to 22 is an increase of 19, which is equivalent to minus 7 modulo 26 (because 3 minus 7 equals minus 4, and plus 26 gives 22). Step 6: From 22 to 15 is a decrease of 7. So effectively, each step in the letter sequence is negative 7 positions. Step 7: Apply the same rule again. From O 15, subtract 7 to get 8, which corresponds to the letter H. Step 8: Therefore, the next term in the series should combine H with 29, giving H29.

Verification / Alternative check:
We can summarise the pattern: letters move as C (3) to V (22) to O (15) to H (8), each time minus 7 positions, while numbers move as 11, 17, 23, 29, each time plus 6. Checking the answer choices, only H29 matches both the required letter and the required number simultaneously. Other combinations such as I29 or H31 fit only one part of the rule, not both.

Why Other Options Are Wrong:
H31 has the correct letter but the wrong number, since 31 does not follow the plus 6 pattern (23 plus 6 equals 29, not 31). I29 has the correct number but the wrong letter because I 9 would represent a decrease of 6, not 7, from O 15. I31 and G29 also break one of the two discovered progressions and so cannot be correct.

Common Pitfalls:
Some candidates focus only on the numbers and pick any option ending with 29, ignoring the letter pattern. Others focus only on the letters and forget to verify the numeric progression. A systematic approach always treats the letters and numbers as two separate sequences and confirms that a candidate option satisfies both rules before selecting it.

Final Answer:
The term that correctly completes the series is H29.