Which three statements are true about snapshot standby databases?

A snapshot standby database is a fully updateable standby database that is created by converting a physical standby database into a snapshot standby database. The main characteristics of a snapshot standby database include:

B: Tablespaces can indeed be dropped in a snapshot standby database because it is updateable and allows all types of DML and DDL operations that do not conflict with the standby role.

C: Tablespaces can be created in a snapshot standby database for the same reasons that they can be dropped; it supports all operations that do not interfere with its standby nature.

E: Tables can be dropped in a snapshot standby database, as it is a fully updateable standby.

Options A and D are incorrect because 'FAILOVER TO' and 'SWITCHOVER TO' commands are not used with snapshot standby databases in these contexts. A failover converts a standby database into the primary role after the original primary has become unavailable, and is not a reversible role transition. Switchover is a planned role reversal between the primary database and one of its standby databases and is not applicable to snapshot standby databases in the context provided.

Option F is incorrect because a logical standby database cannot be converted into a snapshot standby database directly. A logical standby is used for different purposes such as reporting and querying with real-time data, and its structure is different from a physical standby which can be converted into a snapshot standby.