Which THREE statements are true about snapshot standby databases?

A snapshot standby database must be opened at least once in read-write mode before it can be converted into a physical standby database.

A snapshot standby database can be the only standby database in a Maximum Protection Oracle Data Guard configuration.

Snapshot standby databases may be used for rolling database upgrades.

If datafiles grow while a database is a snapshot standby database, then they shrink when converted back to a physical standby database.

A guaranteed restore point is created automatically when a physical standby database is converted into a snapshot standby database.