2、Which two are true about Optimizer Statistics? ❑ A) They do not persist across Instance restarts. ❑ B) They are automatically updated when DDL statements execute. ❑ C) They are gathered by the Manageability Monitor (MMON) background process. ❑ D) They can be gathered by executing the PL/SQL procedures in the DBMS_STATS package. ❑ E) They can be used to determine the events on which a database instance waited. ❑ F) They provide Information to the Optimizer so that it can determine optimal execution plans for SQL statements. • Answer:DF