Which three statements are true about the Oracle Data Dictionary?

Data dictionary views are created by joins of dictionary base tables and DBA-defined tables

The data dictionary is created and maintained by the database administrator

Views with the same name but different prefixes, such as CDB, DBA, ALL and USER, reference the same base tables from the data dictionary

Base tables can be queried directly

It is owned by the SYSTEM user

Usernames of all users including database administrators are stored in the data dictionary