In the mixed alphabet sequence A, Z, Y, B, C, ?, W, D, one letter is missing in the middle. Following the underlying pattern of pairing letters from the beginning and end of the alphabet, which alphabet should replace the question mark?

Introduction / Context:
This question involves a letter series based on the English alphabet. The given sequence is A, Z, Y, B, C, ?, W, D and we are asked to determine the missing letter. Such series often rely on symmetric pairing of letters from the beginning and the end of the alphabet and are very common in mental ability and alphabet test sections of competitive exams.

Given Data / Assumptions:

The given sequence is A, Z, Y, B, C, ?, W, D.
The English alphabet from A to Z contains 26 letters and is assumed in standard order.
The question mark represents exactly one missing letter that must make the pattern consistent.
The sequence is not purely linear but likely interleaves letters from the start and end of the alphabet.

Concept / Approach:
A useful strategy is to notice that A is the first letter and Z is the last letter, so they form a natural pair. Similarly, Y (second from the end) can pair with B (second from the start), and C (third from the start) should pair with X (third from the end). This suggests that the sequence is constructed by alternately taking letters from the beginning and end of the alphabet in symmetric fashion. Recognising this symmetry leads us directly to the missing letter.

Step-by-Step Solution:

Verification / Alternative check:
To verify, write down the paired sequence explicitly as A Z, B Y, C X, D W, and then reorder as A, Z, Y, B, C, X, W, D. This matches the original given series with X filling the missing position. No other letter can preserve this neat symmetric pairing between early and late letters in the alphabet. Therefore, X is the only valid letter that satisfies the underlying structure of the sequence.

Why Other Options Are Wrong:

E would correspond to the fifth letter from the start, which has no symmetric partner shown in this short sequence, so it breaks the pairing rule.

Z is already used as the last letter partner of A; repeating Z at the missing position would destroy the clear one to one pairing pattern.

F is also a later letter from the start but does not match the needed position of the third from the end, and it would disrupt the neat symmetry of the arrangement.

Common Pitfalls:
Some students try to search for simple forward or backward alphabetical progressions without noticing the symmetry between the beginning and end letters. Others ignore the pairing idea and attempt random arithmetic on positions. A quick check of first last, second second last and similar pairs often reveals the correct logic much faster in alphabet series questions of this type.

Final Answer:
The missing alphabet that completes the symmetric pattern is X.