A dot walks round the corners of a hexagon in one direction, drawing each side as it walks along it. Which picture comes next?

Each step the dot moves anticlockwise to the next corner and the side it walked along is drawn. After four steps four sides are drawn, so next there are five sides and the dot is at the end of the fifth side: (b). (a) moves the dot without drawing the side, (c) leaves out the third side and (d) draws the side but leaves the dot behind.