A graph with an (undirected) edge between any two vertices is called a complete graph, and a complete graph containing n vertices is represented by Kn Which of the following figures must not be a plan? 任何两个顶点间都有一条(无向)边的图称为完全图,包含n个顶点的完全图用Kn表示。下列哪个图一定不是平面图?
AK2
BK3
CK4
DK5