单项选择题

A.spanning-tree vlan 2root primary 将配置此交换机为根网桥
B.spanning-tree vlan 2root secondary 将配置此交换机为根网桥
C.spanning-tree vlan 2priority 4096将配置此交换机为根网桥
D.spanning-tree vlan 2root primary 配置后此交换机的优先级变为28672