Which statement about the Adapter FEX feature on the Cisco Nexus 5000 Series Switches is true？（）

• A、 Adapter FEX is a software feature that can be configured on any CNA as long as the Nexus 5000 is running a version of code that supports Adapter FEX
• B、 Adapter FEX can be thought of as a way to divide a single physical link into multiple virtual links or channels.
• C、 Packets on each channel are tagged with an 801.Q header that has a specific source VIF
• D、 When using a dual-homed NIC on the server， active/standby is not supported. Only active/active is supported.