At each step the orange cell moves one row down and two columns to the right (coming back on the other side when it leaves the board), and the blue cell moves one cell clockwise round the edge. One board is wrong. Which?

From (a), the orange cell should go to the second row, third column; then the third row, first column (after wrapping round); then the bottom row, third column; then back to the top-left. The blue cell moves down the right edge and then left along the bottom edge, one cell at a time. In (b) the blue cell is right but the orange cell is in the second column instead of the third, so (b) is wrong.