A cube is made by soldering twelve 3-inch lengths of wire properly at the vertices of the cube. If a fly alights at one of the vertices and then walks along the edges, the greatest distance it could travel before coming to any vertex a second time, without retracing any distance, is:
<spanclass=′latex−bold′>(A)</span>24 in.<spanclass=′latex−bold′>(B)</span>12 in.<spanclass=′latex−bold′>(C)</span>30 in.<spanclass=′latex−bold′>(D)</span>18 in.<spanclass=′latex−bold′>(E)</span>36 in.