Its similar to Question depicted in http://gateoverflow.in/1824/gate2006_48
I have tried on various graphs.
Suppose there is a cycle in A graph then by applying DFS it will generate a non tree edge and in that DFS tree there would always be only one leaf node both u an v if present they cannot be a leaf node at the same moment(As i think)
Therefore i guess the answer to this question is D not C.
Am i right?