A: Auto-failover groups allow you to manage replication and failover of a group of databases on a server or all databases in a managed instance to another region.
E: Because verification of the scale of the outage and how quickly it can be mitigated involves human actions by the operations team, the grace period cannot be set below one hour. This limitation applies to all databases in the failover group regardless of their data synchronization state.
Incorrect Answers:
C: individual SQL Managed Instance databases cannot be added to or removed from a failover group.
Reference:
https://docs.microsoft.com/en-us/azure/azure-sql/database/auto-failover-group-overview