Which of the following packages maintains information in the recovery catalog？ （）

A.CHANGE
B.CATALOG
C.CROSSCHECK
D.SWITCH

A.DELETE SCRIPT
B.ERASE SCRIPT
C.REMOVE SCRIPT
D.UNCATALOG SCRIPT

A.It helps you to determine whether or not the Oracle database is running.
B.It requires the username and password to check the connectivity of the service.
C.It does not require the username and password to check the connectivity of the service.
D.It establishes a session with the database and checks the connectivity of the service.