What are two considerations when using SSO as a network redundancy feature? (Choose two.)

A.	requires synchronization between supervisors in order to guarantee continuous connectivity
B.	the multicast state is preserved during switchover
C.	must be combined with NSF to support uninterrupted Layer 3 operations
D.	both supervisors must be configured separately
E.	must be combined with NSF to support uninterrupted Layer 2 operations