Which letter cluster can replace the question mark (?) to complete the given series? AZFX, EWHW, ?, MQLU, QNNT

Correct — C. Treat the four letter positions as four separate series and solve each one.

Rule: 1st letter +4, 2nd letter −3, 3rd letter +2, 4th letter −1 at every step.

1st: A, E, I, M, Q — rising by 4.
2nd: Z, W, T, Q, N — falling by 3.
3rd: F, H, J, L, N — rising by 2.
4th: X, W, V, U, T — falling by 1.

Reading the third column down gives ITJV — option (c).

Why the others are wrong

• (a)
  IJTV — IJTV has the first and last letters right but swaps the middle two. The second column falls Z, W, T, so T must sit second and J third.
• (b)
  JITV — JITV starts with J. The first column runs A, E, I, M, Q in steps of 4, which fixes I as the opening letter of the missing cluster.
• (d)
  JTIV — JTIV keeps the second and fourth letters right and swaps positions 1 and 3: the first column needs I and the third needs J.

A letter-cluster series is several series stacked side by side. Nothing useful happens if you read a cluster as one unit — the first letters form one arithmetic run, the second letters another, and so on.

Convert to 1-26 numbers and each column becomes plain arithmetic. Here two columns rise and two fall, which is exactly why no single shift describes the cluster as a whole.

Key facts

• A, E, I, M, Q are positions 1, 5, 9, 13, 17 — an arithmetic run of +4.
• Z, W, T, Q, N are positions 26, 23, 20, 17, 14 — falling by 3.
• X, W, V, U, T is the alphabet read backwards one step at a time.

Common traps

• Reading the cluster left to right as a single chain instead of splitting it into columns.
• Finding the right four letters and then ordering them wrongly — every wrong option here is a permutation of I, T, J and V.
• Working only forwards when the blank sits in the middle and can be checked from both sides.

No directly related past PYQ was found.