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

Correct — A. Rule: the seven symbols move through two alternating position cycles, and on every second step the symbol arriving at the bottom-right is swapped for a new one.

Name the cells top-left, top-middle, top-right, centre, bottom-left, bottom-middle, bottom-right.

B sits top-left, top-right, top-left, top-right across figures 1 to 4, so figure 5 puts it top-left. T sits bottom-middle, centre, bottom-middle, centre, so figure 5 puts it bottom-middle.

Figure 4 reads = L B / T / V D 3. Carrying it through the same step that turned figure 2 into figure 3 gives B D V on top, L in the centre, 3 T on the bottom.

That step also replaced the arriving symbol: X left the top-left of figure 2 and came back as L at the bottom-right of figure 3. So figure 5 must end in a symbol figure 4 does not have — 4 — which is option (a).

Why the others are wrong

• (b)
  T is top-middle here and 4 is top-left. Across figures 1 to 4, T only ever occupies the centre or the bottom-middle, so this figure breaks the anchor.
• (c)
  T is top-middle again and B is top-left with T beside it, a pairing no given figure shows. The two-cell oscillation of B and T is broken.
• (d)
  Six cells are right, but the bottom-right keeps =, a symbol already in figure 4. The step that produced figure 3 replaced the arriving symbol rather than repeating it.

A symbol series is a position problem, not a picture problem. Number the cells and track where each individual symbol travels from one figure to the next.

Two things then fall out. Symbols that oscillate between two cells — B and T here — fix the frame and knock out half the options at a glance.

And a symbol that appears from nowhere marks a substitution the setter has built in: figures 1 and 2 use the set B D X = 3 T V, figures 3 and 4 replace X with L, so figure 5 is due a fresh symbol of its own.

Key facts

• In figures 1 to 4, B occupies only the top-left or top-right cell.
• In figures 1 to 4, T occupies only the centre or the bottom-middle cell.
• Figures 1 and 2 use the symbols B D X = 3 T V, and figures 3 and 4 replace X with L.

Common traps

• Reading the grid as a whole-figure rotation instead of tracking symbols one at a time
• Missing that the symbol set itself changes every two figures
• Settling for the option that matches six cells out of seven

No directly related past PYQ was found.