In the following question, various terms of an alphabet series are given with one or more terms missing as shown by (?). Choose the missing term: Y, B, T, G, O, ?

Introduction / Context:
This alphabet series question involves two interleaved sequences, one using letters that move backward along the alphabet and the other using letters that move forward. Candidates must separate these two hidden series and fill the missing term. The given sequence is Y, B, T, G, O, ?.

Given Data / Assumptions:
- Series: Y, B, T, G, O, ?- Letters are in the English alphabet, where A is 1 and Z is 26.- Every alternate term may belong to a separate subsequence.

Concept / Approach:
For alphabet series, a good technique is to separate the terms at odd and even positions and study them as two independent sequences. Often, one subsequence will show a clear progression forward, while the other may move backward with a fixed step. After figuring out both subsequences, we can identify the missing term at the appropriate position.

Step-by-Step Solution:
- Write positions explicitly: 1st = Y, 2nd = B, 3rd = T, 4th = G, 5th = O, 6th = ?- Consider the letters at odd positions: 1st Y, 3rd T, 5th O.- Convert them to numerical positions: Y = 25, T = 20, O = 15.- Differences: 25 → 20 is -5, 20 → 15 is -5. So the odd position series decreases by 5 each time.- Now consider the letters at even positions: 2nd B, 4th G, 6th ?.- Convert to numeric: B = 2, G = 7.- Difference: 2 → 7 is +5. So the even position series increases by 5 each time.- Next even term should be 7 + 5 = 12, which corresponds to the 12th letter of the alphabet.- The 12th letter is L.- Therefore, the missing term at the 6th position is L.

Verification / Alternative check:
- Reconstruct odd positions: 25 (Y), 20 (T), 15 (O) are obtained by repeatedly subtracting 5.- Reconstruct even positions: 2 (B), 7 (G), 12 (L) are obtained by repeatedly adding 5.- Combining them gives the final series: Y, B, T, G, O, L, which is fully consistent.

Why Other Options Are Wrong:
- N, M, K and J do not correspond to the expected numeric position 12.- Choosing any of these letters would break the consistent step of plus 5 in the even position subsequence.

Common Pitfalls:
- Not separating the series into odd and even positions causes confusion because the combined sequence appears irregular.- Some candidates may try to measure differences between consecutive letters directly, which does not reveal a simple pattern here.- Miscounting alphabet positions can also lead to wrong answers even after spotting the correct step size.

Final Answer:
The even position subsequence increases by 5 in alphabet positions, so the missing letter is the 12th letter, L.