下图是某图的深度优先生成树，判断结点2是关节点的原因( )\n \n \n \n \n \n \n

\n \n \n \n A.\n L(5)＞=DFN(2)\n

\n \n

\n \n \n \n B.\n L(6)＞DFN(2)\n