Item 4.2.1.a.
This is not a tree since it contains a cycle. Note also that there are too many edges to be a tree, since we know that all trees with \(v\) vertices have \(v-1\) edges.
This is not a tree since it contains a cycle. Note also that there are too many edges to be a tree, since we know that all trees with \(v\) vertices have \(v-1\) edges.