An arrow turns through the same angle, in the same direction, from each box to the next. Which answer figure should come in place of the question mark?

Each step the arrow turns $135^{\circ }$ clockwise: up, down-right, left, up-right. One more $135^{\circ }$ clockwise turn from up-right makes it point straight down: (a). (b) turns only $90^{\circ }$, (c) turns the wrong way and (d) turns $180^{\circ }$.