In the following statements about graph operations，which one is NOT correct

A．Finding critical path is an operation on directed graph

B．Finding critical path is an operation on undirected graph

C．Spanning tree of a graph may not be unique

D．Minimum spanning tree of a graph may not be unique

常引起视神经孔增大的病变是（）

A.骨纤维异常增殖症

B.畸形性骨炎

C.石骨症

D.眶内血管瘤

E.视神经脑膜瘤