Select the figure from among the given options which when put in place of the question mark (?) will logically completethe series.

Correct — B.

The rectangle and its four cells never change. Only the small circle moves, and it uses eight stations: beyond the four corners of the rectangle and beyond the midpoints of its four sides.

Rule: the circle moves three stations anticlockwise at each step.

Top-right corner, then middle-left, then bottom-right corner, then top-centre.

Three stations anticlockwise from top-centre is the bottom-left corner, with the rectangle untouched: option (b).

Why the others are wrong

• (a)
  The circle sits at the top-left, one station anticlockwise from top-centre rather than three. The rectangle is right but the step is far too short.
• (c)
  The rectangle has been redrawn with crossed diagonals instead of its four cells, and the circle is parked at the middle-right.
• (d)
  The rectangle is cut into three horizontal bands, which the series never does, and the circle repeats the middle-left station used earlier.

A figure series with one moving element is read by naming the track before measuring the step. The track here is the ring of eight stations round the rectangle.

Number them clockwise with the top-left corner as 1, so top-centre is 2, top-right 3, middle-right 4, bottom-right 5, bottom-centre 6, bottom-left 7 and middle-left 8.

The four panels then read 3, 8, 5, 2: each step subtracts three modulo eight, a three-station anticlockwise move. From 2, three back wraps round to 7 — the bottom-left corner.

The second thing to settle is what does not change. The rectangle keeps the same four cells in every panel, so an option that alters its inner lines is out before its circle is even looked at.

Key facts

• The eight stations round a figure are its four corners and the midpoints of its four sides.
• Three stations anticlockwise is the same as five clockwise on a ring of eight.
• The circle here runs top-right corner, middle-left, bottom-right corner, top-centre.

Common traps

• Counting the step as one station because consecutive panels look neighbourly
• Tracking the circle and missing that an option has redrawn the rectangle
• Reading the move as three stations clockwise, which lands on the bottom-right corner and matches no option

No directly related past PYQ was found.