Which three statements are true regarding standby redo logs?

Standby redo logs are used in Data Guard environments for a number of reasons. Which three statements are true regarding standby redo logs?

A.
They are required to implement a no-data-loss disaster recovery solution.

B.
They are used on the primary database to allow the primary and a standby database to switch roles easily and quickly without additional DBA intervention.

C.
They must be archived before being applied to a standby database, requiring the ARCH process to be running on the standby irrespective of the archive log mode.

D.
They must be updated on the standby database server in asynchronous mode to guarantee data availability.