In terms of graph theory, the following statement is incorrect ( ).

A、Ifatreehasnnodes,thenumberofitsedgesisn-1.
B、Ifthereisonemoreedgeinthetree,theremustbeacircle.
C、Nodesinatreemaynotbeconnectedtoeachother.
D、Ifanedgeisremovedfromatree,thetreewon’tbeconnected.