Data files of which three tablespaces can be recovered by performing an open recovery？（）

A.The database performance would be enhanced.
B.The redo log files would be get filled more frequently.
C.The overall database performance would be degraded.
D.The mean time to recover （MTTR） would be increased.

A.It is not possible to disable the primary key constraint.
B.It is possible to have more than one primary key constraint in a single table.
C.The primary key constraint can be referred by only one foreign key constraint.
D.The primary key constraint can be imposed by combining more than one column.
E.The non-deferrable primary key constraint creates an unique index on the primary key column if it is not already indexed.

A.use the external table population
B.use the Oracle Data Pump export and import utility
C.use the conventional path data load of SQL*Loader utility
D.use the direct path data load of Oracle export and import utility