Consider an undirected graph G that is connected. If we perform a depth$-$first search starting from vertex v$,$ how do we know whether G contains a cycle?

Group of answer choices

G contains a cycle whenever there is a DFS edge found during the DFS$.$

G contains a cycle whenever there is a back edge found during the DFS$.$

G always contains a cycle, no matter what happens during the DFS$.$

G cannot contain a cycle, no matter what happens during the DFS$.$