单项选择题

A.All ports will be in forwarding mode.
B.All ports in VLAN 10 will be in forwarding mode.
C.All ports in VLAN 10 will be in forwarding mode and all ports in VLAN 20 will be in blocking mode.
D.All ports in VLAN 10 will be in forwarding mode and all ports in VLAN 20 will be in standby mode.