You have configured a Cisco Catalyst switch to perform Layer 3 routing via an SVI and have assigned that interface to VLAN 20. To check the status of the SVI， you issue the show interfaces vlan 20 command at the CLI prompt. You see from the output display that the interface is in an "up/up" state. What must be true in an SVI configuration to bring the VLAN and line protocol up？（）
- AThe port must be physically connected to another Layer 3 device.
- BAt least one port in VLAN 20 must be active.
- CThe Layer 3 routing protocol must be operational and receiving routing updates from neighboring peer devices.
- DBecause this is a virtual interface， the operational status will always be in an "up/up" state.