Which three statements are true about SQL plan directives?（）

A、A. They are tied to a specific statement or SQL id.

B、B. They instruct the maintenance job to collect missing statistics or perform dynamic sampling to generate a more optimal plan.

C、C. They are used to gather only missing statistics.

D、D. They are created for a query expression where statistics are missing or the cardinality estimates by the optimizer are incorrect.

E、E. They instruct the optimizer to create only column group statistics.

F、F. Improve plan accuracy by persisting both compilation and execution statistics in the SYSAUX tablespace.