When a staging server is used as an environment for testing new data in a default WebSphere Commerce installation， which of the following are true about the staging server？（）

A.The database has a subset of the tables in the production server database.
B.The database has a copy of selected data from the production database
C.The database logs changes for later propagation.
D.The database is accessed as read-only to prevent data corruption.
E.The database includes all user and order data for offline processing.