Positions (i), (ii) and (iii) belong to one cube. Which of the cubes (a) to (d) CAN be another position of the same cube?

Z is seen with H, K, M and Q, so Z is opposite X; Q is seen with M, Z, X and H, so Q is opposite K, and M is opposite H. (a) shows K beside Q and (d) shows H beside M, so both are impossible. (b) and (c) show the same three letters K, M and Z, but only (c) has them in the right order round the corner; (b) is a mirror image.