Which three statements are true about the Oracle Data Dictionary? (Choose three.) 

Answer options:

A. Data dictionary views are created by joins of dictionary base tables and DBA-defined tables
B. The data dictionary is created and maintained by the database administrator
C. Views with the same name but different prefixes, such as CDB, DBA, ALL and USER, reference the same base tables from the data dictionary
D. Base tables can be queried directly
E. It is owned by the SYSTEM user
F. Usernames of all users including database administrators are stored in the data dictionary

CDF