(of) The number 2 will we opposite the number, 4 thenumber 1 will we opposite the number 6 and number 5 will we opposite the number 3. Figure (a) has the number 1 and 6 on adjacent faces, figure (b) has the number 3 and 5 on adjacent faces, figure (c) has the numbers 2 and 4 on the adjacent faces. So, these three alternatives are not possible. Since, the number 1,3 and 4 can appear on adjacent faces. So figure (d) is possible.