In this series one line is added to the drawing at every step, starting from the dot. Which figure comes next?

Each new line turns clockwise from the last one, and the lengths go 1, 1, 2, 2, 3, … (each length is used twice). The figure in the last box ends with a line of length 3 going right, so the next line goes DOWN with length 3: (a). (b) keeps length 2, (d) jumps to length 4 and (c) adds two lines at once.