## Thinking Mathematically (6th Edition)

One characteristic of a tree is the following: If the graph has $n$ vertices, then the graph has $n-1$ edges. To make a spanning tree from the original graph, we can use the edges BA, AD, DC, CF, and FE. The spanning tree has 6 vertices and 5 edges and every edge is a bridge. The spanning tree is connected and there are no circuits. Therefore, this is a valid spanning tree. This is one spanning tree, but other spanning trees are possible.