If two cycle graphs Gm and Gn are joined together with a vertex, the number of spanning trees in the new graph is ______

If two cycle graphs Gm and Gn are joined together with a vertex, the

1.	If two cycle graphs Gm and Gn are joined together with a vertex, the number of spanning trees in the new graph is ______
A.	m+n-1
B.	m-n
C.	m*n
D.	m*n+1
Answer» D. m*n+1