Final answer:
A solid square-based pyramid with all its corners cut off results in an octahedron, which has 13 edges.
Step-by-step explanation:
A solid square-based pyramid with all its corners cut off results in a shape known as an octahedron. An octahedron has 8 faces, 6 corners, and 12 edges. To find the number of edges in the resulting shape, we add the edges of the original square-based pyramid to the edges created by cutting off the corners. The original pyramid has 8 edges, and each corner cut off introduces 3 new edges. Therefore, the resulting shape has 8 + (6 x 3) = 26 edges. However, since each of these edges is shared by two faces, we must divide by 2 to get the final answer. Therefore, the resulting shape has a total of 26 / 2 = 13 edges. So, the correct answer is not given in the options provided.