Which two are prerequisites for configuring flashback database for Oracle 12c databases, in a Data Guard environment? 

Answer options:

A. A flash recovery area must be configured.
B. The database must be in MOUNT state.
C. The database must be in ARCHIVELOG mode.
D. A far sync instance must be configured to flash back a standby when the primary has been flashed back.
E. The Data Guard Broker must be used.

AC

Configure the following database settings before enabling Flashback Database: You must have a fast recovery area enabled, because flashback logs can only be stored in the fast recovery area. Your database must be running in ARCHIVELOG mode, because archived logs are used in the Flashback Database operation. For Oracle Real Application Clusters (Oracle RAC) databases, the fast recovery area must be in a clustered file system or in ASM. References: https://docs.oracle.com/database/121/BRADV/flashdb.htm#BRADV582