An orange counter moves diagonally across the board, one cell per step, and bounces off any edge it reaches, like a ball. Which board comes next?

The counter moves one cell down and one cell right each step until it hits the right edge, then it bounces and moves down and left, reaching the bottom row. There it bounces again and now moves up and left: from the bottom row, second cell from the right, to the third row, second cell from the left: (b). (a) goes back the way it came, (c) slides along the bottom and (d) moves two cells.