What type of protection is implemented when the DBA issues the ALTER DATABASE SET STANDBY DATABASE PROTECTED； command？（）

A.An improved version of multithreaded server configuration. 
B.A connection pooling configuration where several clients are connected to the same server process. 
C.Two more database servers, which share data by means of database links; the client software is unaware to which server it is connected. 
D.A configuration of Real Application Cluster where the client connection is routed to the least busy instance. 

A.The CONNECT INTERNAL is disallowed. 
B.The Server Manager tool is no longer supplied. 
C.The listener must be running to make a connection. 
D.The use of remote password login file (orapw<sid>) is unchanged.

A.The size of the redo buffer in SGA. 
B.The instance that will perform recovery in Real Application Cluster database. 
C.The number of blocks to be read during instance recovery, or the time needed to complete instance recovery. 
D.The number of passes through the redo logs made by the recovery process to identify blocks needing recovery.