which two cases is it possible to change the protection…

In which two cases is it possible to change the protection mode to maximum protection using Enterprise
Manager Cloud Control?

A.
A snapshot standby database is the only standby database in the Data Guard configuration.

B.
A logical standby database is the only standby database in the data guard configuration.

C.
A far sync instance is the only Data Guard configuration member receiving redo in synchronous mode.

D.
Flashback is not enabled for either the primary database, the standby database, or both in the Data Guard
configuration.

E.
The primary and standby databases are hosted on different operating systems.

Explanation:
Maximum protection mode requires the SYNC redo transport mode to be set on at least one standby database.
Note:
The Maximum protection mode ensures that no data loss will occur if the primary database fails. To provide
this level of protection, the redo data needed to recover a transaction must be written to both the online redo
log and to the standby redo log on at least one synchronized standby database before the transaction commits.
To ensure that data loss cannot occur, the primary database will shut down, rather than continue processing
transactions, if it cannot write its redo stream to at least one synchronized standby database.
http://www.oracle.com/technetwork/oem/framework-infra/wp-em12c-building-ha-level3-
1631423.pdf