Select the figure from among the given options that can replace the question mark (?) in the following series.

Correct — A. Each box holds six vertical stems. The three on the left carry a shape at the top of the stem, the three on the right carry a shape at the bottom.

Box 1: top row triangle, triangle, triangle — bottom row circle, circle, circle.
Box 2: the leftmost top triangle has become a circle.
Box 3: the rightmost bottom circle has become a triangle.
Box 4: the second top triangle has become a circle.

Rule: exactly one shape changes per step, and the two rows take turns — the top row converts triangles to circles from the left, the bottom row converts circles to triangles from the right.

Box 5 is the bottom row's turn, so the second circle from the right becomes a triangle. Top row circle, circle, triangle; bottom row circle, triangle, triangle — option (a).

Why the others are wrong

• (b)
  Option (b) converts in the top row, leaving it all circles, when the alternation makes it the bottom row's turn. It also draws two bottom triangles pointing downwards, an orientation the printed boxes never use.
• (c)
  Option (c) has the bottom row right but scrambles the top into circle, triangle, circle. The top row converts strictly left to right, so once the second shape is a circle it stays one.
• (d)
  Option (d) converts in the bottom row but at the wrong end — it changes the leftmost circle. The bottom row works right to left, so the circle beside the existing triangle is the one that goes.

This is a conversion series, not a movement series. Nothing travels; each step swaps exactly one shape for the other kind, and the puzzle is which one and in what order.

Two counters run at once. The top row turns triangles into circles from the left, the bottom row turns circles into triangles from the right, and the rows alternate.

Once you see that only one shape changes per box, comparing consecutive boxes beats reading each box whole.

Key facts

• Every box in the series has six stems, three with a shape at the top and three with a shape at the bottom.
• Exactly one shape changes between any two consecutive boxes.
• The top row converts triangles to circles starting from the left, and the bottom row converts circles to triangles starting from the right.
• Every triangle in the four printed boxes points upwards.

Common traps

• Choosing an option that converts in the top row when the alternation calls for the bottom row
• Missing the direction each row runs in and converting from the wrong end
• Accepting an inverted triangle as the same shape

No directly related past PYQ was found.