A circle cut into quarters (A) is redrawn as a circle cut into eighths (B). Which answer shows C redrawn in the same way?

B shades exactly the same part of the circle as A, now covered by two eighths instead of one quarter. C has two quarters shaded (top-left and bottom-left), so the answer shades the four eighths covering that same half: (d). (a) shades only one quarter's worth, (b) is shifted round by one eighth and (c) has only three eighths.