Four symbols sit in the corners of a square, and at every step two of them change places. Which figure comes next?

First the top pair swaps, then the right-hand pair, then the bottom pair, then the left-hand pair — the swap moves round the square clockwise. Next it is the top pair's turn again: A and % change places, giving % top-left, A top-right, @ bottom-right, # bottom-left — (b). (a) turns every symbol one corner clockwise, (c) swaps the right-hand pair and (d) swaps a diagonal pair.