The coloured net at the top is folded into a cube. Which of the cubes (a) to (d) is that cube?

From the net: red is opposite green, blue is opposite violet and yellow is opposite black. (b) shows green beside red and (d) shows blue beside violet, so both are impossible. (a) shows red, yellow and blue, which do meet at a corner, but going round the wrong way: it is a mirror image. (c) fits.