The figures I, II and III are parts of a sequence. Which one of the following…

Two features change in step across the sequence: the measure of the shaded sector and the radius where the shading begins. The shaded measure grows by \(45^\circ\) per figure — \(90^\circ\), then \(135^\circ\), then \(180^\circ\) — so the next figure must shade \(225^\circ\), which is \(\frac{5}{8}\) of the circle. The starting radius advances one quarter turn clockwise per figure — 9 o'clock, then 12 o'clock, then 3 o'clock — so the next figure's shading must begin at 6 o'clock and sweep clockwise past 9 and 12 o'clock, ending at the 1:30 direction and leaving a \(135^\circ\) unshaded wedge facing the right. This is the drawing with the required sweep and orientation.