BMAT 2016 · Question 23 · Spatial

The drawing below shows the outlines of three pieces of card (one square and two right angled triangles) which all fit exactly around the same size circle.

The pieces of card are pinned together through the centres of the circles and each of the card shapes can be rotated about the pin so that together the three shapes make an interesting outline. Which one of the following is a possible outline of the three shapes?