Which statement regarding CBO (Cost-based optimizer) and RBO (Rule-based optimizer) is true?

Oracle database release 10g is able to use new database statistic features for tables and index.

Which statement regarding CBO (Cost-based optimizer) and RBO (Rule-based optimizer) is true? There are 3 correct answers to this question.
A . In Oracle 10g, both CBO- and RBO-based index statistics can be used simultaneously.
B . Database statistics can be managed automatically in Oracle 10g. This is implemented in the database as the dbms_scheduler job GATHER_STATS_JO
C . However, this method is not yet supported and is deactivated to avoid conflicts with the brconnect methods.
D . Oracle 10g only supports CBO, while the RBO is not supported anymore.
E . As of Oracle 10g, you are required to create statistics for the Oracle dictionary as well.

Answer: B,C,D