You are about to migrate a customer network to use a VSS. Which of these statements is true about a VSS？ （）
- A The VSS switch must be the root bridge for all VLANs and is automatically designated
- B The VSS switch is defined in RFC 4318 as a managed object
- C The PAgP+ or LACP protocols are used to maintain the operational state of the VSS devices
- D A VSS interoperates with a virtual port channel
- E The 802.1Q or ISL protocols are used to maintain the operational state of the VSS devices
- F A VSS increases the size of the spanning-tree domai