Which figure should replace the question mark (?) if the following series were to be continued?

Correct — C. Every box holds six letters: one at the top left, four across the middle, one at the bottom right.

Box 1: A / B L U E / M
Box 2: L / A B E M / U
Box 3: U / M A B T / L
Box 4: A / U M T L / B

Rule for the step you need: the two corner letters swap, and the four middle letters slide one place to the right, the last wrapping round to the front.

Apply it to box 4. Corners A and B swap, so the fifth box opens with B and closes with A. The middle U M T L slides to L U M T.

The fifth box must therefore read B / L U M ? / A, and option (c) is B / L U M H / A.

Why the others are wrong

• (a)
  Option (a) is B / M T L H / A. The corners are right, but the middle should slide U M T L to L U M T; M T L H has dropped U out of the box altogether.
• (b)
  Box 4's corners are A and B, so after the swap the answer has to open with B and close with A. Option (b) is U / A T M B / L, opening with box 3's top-left letter instead.
• (d)
  Option (d) is U / B T M A / L — the same wrong corners as (b), with A and B parked in the middle row. The slide moves middle letters among themselves and never pulls a corner letter inwards.

A letter-box series is a positional puzzle first and an alphabet puzzle second. Write each box as one string in a fixed reading order — top-left, the four middles left to right, bottom-right — and the movement becomes visible.

Do that here and the boxes read ABLUEM, LABEMU, UMABTL and AUMTLB.

The steps then alternate between two shuffles.

Boxes 1 to 2 and 3 to 4: top-left drops to middle 1, middle 1 to middle 2, middle 2 climbs to top-left,
and middle 3 drops to bottom-right, bottom-right to middle 4, middle 4 back to middle 3.

Boxes 2 to 3 and 4 to 5: the corners swap and the middle four slide one place right with a wrap.

Key facts

• Read top-left, then the middle four, then bottom-right, the four printed boxes are ABLUEM, LABEMU, UMABTL and AUMTLB.
• Option (c) read the same way is BLUMHA.
• From box 4 to box 5 the corners swap and the middle four slide right with a wrap, so U M T L becomes L U M T.
• A, B, L, M and U appear in all five boxes, while the sixth letter runs E, E, T, T, H.

Common traps

• Hunting for a single rule when the steps alternate between two
• Deciding on the one new letter instead of on the letters that carry over
• Reading the middle row alone and ignoring the two corner letters

No directly related past PYQ was found.